Stone Age to Life for Primary-School Pupils

Winter 2012 Issue 25 How many schools and teachers do you reach – The European journal for science teachers worldwide? In this issue: Accelerating the pace of science: interview with CERN‘s Rolf Heuer Also:

Science in the open: bringing the Stone Age to life for primary-school pupils

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Published by EIROforum: ISSN: 1818-0353

Subscribe (free in Europe): www.scienceinschool.org Published and funded by EIROforum Editorial About Science in School The European journal for science teachers Science in School is the only teaching journal to cover all sciences and target the whole of his print copy of Science in School has a mass Europe and beyond. Contents include cutting- of nearly a quarter of a kilogram. But do you edge science, teaching materials and much more. know how a kilogram is defined? And did you know that the definition may be about to Brought to you by Europe’s top scientific research institutes change,T with the help of CERN (page 59)? Does this Science in School is published and funded by have anything to do with the Higgs, you might ask? It EIROforum (www.eiroforum.org), a partnership doesn’t, in fact, but we’re proud to have CERN’s direc- between eight of Europe’s largest intergovern- tor general, Rolf Heuer, share his excitement about the mental scientific research organisations. Higgs boson (page 6). Inspiring science teachers worldwide The discovery of this new boson is certainly a historic moment in physics, The Science in School website offers articles perhaps comparable to Galileo Galilei’s discovery of Jupiter’s moons in the in 30+ languages and is read worldwide. The free quarterly journal is printed in English and th 17 century. Now you and your students can follow in his footsteps, re-dis- distributed across Europe. covering the motions of these celestial bodies (page 41). If you’re a chemistry teacher, however, you may be more interested in how another cornerstone of Advertising: tailored to your needs science, the periodic table, is still under development, with scientists striving Choose between advertising in our print to create the next heaviest element (page 18). journal, or on our website. For maximum And during your stroll through history, you could step all the way back into impact, reach our entire readership with an advertorial (online and in print). Online and in the Stone Age with your pupils, with an outdoor project for primary school print, we have a total of 100 000 readers per (page 48). As far as we know, people in the Stone Age didn’t have soap, but quarter. the Babylonians, 5000 years ago, did. Today, scientists are adapting this old in- · The majority of our readers are secondary- vention by making magnetic surfactants (page 22), which could, for example, school science teachers. be used to clean up oil spills before they spread through the ocean, following · Our readership also includes many primary- the currents. school teachers, teacher trainers, head teachers and others involved in science Ocean currents and waves are a complex and exciting topic, although they education. aren’t always addressed outside geography lessons. With the help of some · The journal reaches significant numbers simple activities, however, your students can explore the physics of the ocean of key decision-makers: at the European for themselves (page 28). Commission, the European Parliament and in Out on the open seas, fishermen need to pay careful attention to currents as European national ministries. they search for fish. On a microscopic scale, scientists at EMBL are also con- For more information, see www.scienceinschool.org/advertising or cerned with fishing – the way that microtubules ‘fish’ the chromosomes apart contact [email protected] during cell division. It turns out that the process is rather inaccurate, which is one cause of infertility (see page 13). Subscribing Bringing cutting-edge science such as this into the classroom can be a power- Register free online to: ful motivating factor for your students – and of course it’s part of the purpose · Subscribe to the e-newsletter of Science in School. To help you do this, we’ve got some ideas on how to · Request a free print subscription introduce and analyse research papers with your students (page 36). Alterna- (limited availability) tively, you could use some of our simply written but informative science arti- · Post your comments. cles; for example, you could introduce your students to the science involved How can I get involved? in orthodontics (page 54) or to the mystery of altruism (online only). Science in School relies on the involvement of Science in School, of course, relies on the altruism of many of its readers, so teachers, scientists and other experts in science why not get more involved? You could translate articles so that we can share education. · Submit articles or reviews them with other teachers in your country; review articles to ensure they are up · Join the referee panel to standard; review websites and other materials; or submit your own articles. · Translate articles for publication online And of course, you can spread the word about Science in School, for example · Tell your colleagues about Science in School by ‘liking’ our Facebook page. · Make a donation to support the journal. See www.scienceinschool.org or contact us. We wish you a cosy wintertime and look forward to seeing you in 2013! Contact us Marlene Rau Dr Eleanor Hayes / Dr Marlene Rau Editor of Science in School Science in School [email protected] European Molecular Biology Laboratory www.scienceinschool.org To learn how to Meyerhofstrasse 1 use this code, see 69117 Heidelberg page 65. Germany i I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Contents

Image courtesy of CERN i Editorial News from the EIROs 2 Cool and hot science for a bright future

Feature article 6 Accelerating the pace of science: interview with 6 CERN’s Rolf Heuer

Image courtesy of schoeband; image source: Flickr Cutting-edge science 13 Sloppy fishing: why meiosis goes wrong 18 The numbers game: extending the periodic table 22 Magnetic science: developing a new surfactant

Teaching activities 28 Movers and shakers: physics in the oceans 22 36 Exploring scientific research articles in the classroom

Image courtesy of somebody_; image source: Flickr Science education projects 41 Galileo and the moons of Jupiter: exploring the night sky of 1610 48 Science in the open: bringing the Stone Age to life for primary-school pupils

Science topics 28 54 The changing face of orthodontics 59 Weighing up the evidence: what is a kilo? Image courtesy of Ramessos; image source: Wikimedia Commons

Additional online material

Science and Society The mystery of altruism 48

Image courtesy of lanuiop; image source: Flickr

Forthcoming events for schools: www.scienceinschool.org/events To read the whole issue, see: www.scienceinschool.org/2012/issue25

54 To learn how to use this code, see page 65. www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 1 Cool and hot science for a bright future Science in School is published by EIROforum, a collaboration between eight of Europe’s largest inter-governmental scientific research organisations. This article reviews some of the latest news from the EIROforum members (EIROs).

CERN: proudly EFDA-JET: paving presenting the new (Higgs?) the tungsten-tile road to ITER boson ITER, the world’s biggest fusion experiment, is under construction in the south of France. During its construction, On 4 July 2012, the ATLAS and CMS experiments at the Joint European Torus (JET) – currently Europe’s largest CERN’s Large Hadron Collider (LHC) announced the dis- fusion experiment – is a vital test bed for ITER design and covery of a new particle with a mass of about 126 GeV and operation. characteristics similar to those expected for the long-sought Higgs boson. This discovery is a major step forward in our In this capacity, JET has successfully completed its 2011-2012 understanding of the origin of mass, and of the fundamental experimental campaign by running 151 identical high-powered properties of matter, space and time. plasma pulses, totalling 900 seconds of stable operating time. This emulates a single pulse of ITER – by virtue of its supercon- The preliminary results come from data taken in 2011 and ducting magnets, ITER will be able to maintain a stable pulse 2012, corresponding to about 1015 proton-proton collisions at 20 times longer than JET. On the basis of the recent experi- 7 and 8 TeV energy. More data will be needed to study the ments, scientists are confident that they will be able to maintain different decay modes of the new particle, to find out if the stable fusion conditions for the length of these longer pulses. theoretical predictions are correct, or if there are any – even The experiment also tested the long-term behaviour of the wall tiny – differences between the predictions of the Higgs model materials – a range of JET’s wall tiles will now be extracted by and the observations. the remote-handling system (pictured) for analysis. Find out more about the search for the Higgs in this issue’s feature The ITER design team are very interested in the results, and article: have already requested an even more severe test for the materi- Hayes E (2012) Accelerating the pace of science: interview als when experiments recommence next year: deliberate melt- with CERN’s Rolf Heuer. Science in School 25: 6-12. ing of some tungsten wall tiles. www.scienceinschool.org/2012/issue25/heuer To learn more about how the LHC works and the search for the Situated in Culham, UK, JET is Europe’s fusion device. Scientific Higgs boson, see: exploitation of JET is undertaken through the European Fusion

Landua R, Rau M (2008) The LHC: a step closer to the Big Bang. Development Agreement (EFDA). To learn more, see: www.efda. Image courtesy of EFDA-JET Science in School 10: 26-33. www.scienceinschool.org/2008/ org issue10/lhcwhy For a list of EFDA-JET-related articles in Science in School, Image courtesy of CERN Landua R (2008) The LHC: a look inside. Science in School 10: see: www.scienceinschool.org/efdajet 34-45. www.scienceinschool.org/2008/issue10/lhchow Based in Geneva, Switzerland, CERN is the world’s largest particle physics laboratory. To learn more, see: www.cern.ch The remote handling mascot is mount- For a list of CERN-related articles in Science in School, see: ed on a 6 m articulated boom, which www.scienceinschool.org/cern allows maintenance without humans entering the JET vessel. An operator One of the proton-proton collisions at a in a remote control room controls the centre of mass energy of 8 TeV, recorded mascot’s two gripper arms, which can with the CMS detector, which contributed to the discovery of the new particle. operate around 1500 bespoke tools.

2 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Image courtesy of EMBL-EBI News from the EIROs

ENCODE researchers found that most of our DNA has a function: controlling when Biology and where genes are turned on and off. Chemistry Image courtesy of ESA / AOES Medialab

ESA’s Earth Explorer CryoSat mission is dedicated to precisely monitoring changes in the thickness of marine ice floating on the polar oceans, and variations in the thickness of the vast ice sheets that Physics blanket Greenland and Antarctica. EMBL: ENCODEing the switch- ESA: The Arctic ice cap is thinning board of the human genome The year 2012 saw the surface area of Arctic sea ice hit a record low since satellite measurements began in the 1970s. The For the past five years, hundreds of scientists in the ‘Encyclo- consequence of losing part of the Arctic’s ice coverage could be paedia of DNA elements’ (ENCODE) project have been sys- profound: the ice cap reflects sunlight back into space; sunlight tematically exploring what the human genome does, to iden- that, unless reflected, would contribute to global warming. tify all its functional elements. Their findings show that much The European Space Agency (ESA)’s satellites SMOS and of what has been called ‘junk DNA’ is actually a massive, 3D CryoSat have found that not only is the area of sea-ice getting switchboard turning genes on and off. Together with colleagues smaller but the ice is also getting thinner: 900 km3 of sum- from around the globe, scientists at EMBL’s European Bioin- mer sea ice have disappeared from the Arctic ocean over the formatics Institute have found that while only 2% of our DNA past year, a rate of loss that is 50% higher than most scenarios is genes, a much bigger part of the genome – at least 20% – is outlined by polar scientists. involved in controlling when and where those genes are active, In addition to the total ice volume, it is important to evalu- and as much as 80% of the genome has a distinct biochemical ate the thickness of the young ice that forms in winter. Only activity. This opens up new avenues of biomedical research. those areas thick enough to survive the next summer’s melting To give some sense of the scale of the project, ENCODE used period can become the basis of the following winter’s thick around 300 years’ worth of computer time studying 147 tissue ice. It is this thick, multi-year ice that ultimately indicates how types to determine what turns specific genes on and off, and healthy the Arctic is. how that ‘switch’ differs between cell types. All of the data is ESA’s measurements show that this newly formed ice is be- now publicly available and the findings are published in 30 coming significantly thinner each year, so that less and less of connected, open-access papers in three science journals: Nature, it survives the summer. In particular, SMOS detected extensive Genome Biology and Genome Research. areas less than half a metre thick. Scientists therefore predict For more details including the full publication list, see the press that of the total Arctic sea-ice cover for Winter 2012-13, a larger release on the EMBL website (www.embl.org) or use the direct fraction than ever before (about 12 million km2) will consist of link: http://tinyurl.com/ebiencode thin ice. This suggests that less Arctic sea-ice than ever before What is the ENCODE project all about? Watch a video interview will survive the melting phase in Summer 2013. with leading scientists Ewan Birney, Tim Hubbard and Roderic Guigo: http://bit.ly/Ro9UDt To model the effect of the changing ice cover with your students in class, see: Learn how the insights from the ENCODE project were repre- sented in the ‘Dance of the DNA’. Visit the website of the Science Shallcross D, Harrison T (2008) Climate change modelling Museum, London, UK (www.sciencemuseum.org.uk) or use the in the classroom. Science in School 9: 28-33. direct link: http://tinyurl.com/8cr7249 www.scienceinschool.org/2008/issue9/climate EMBL is Europe’s leading laboratory for basic research in molecu- See our article series on climate change in several languages: lar biology, with its headquarters in Heidelberg, Germany. The www.scienceinschool.org/climatechange European Bioinformatics Institute is part of EMBL and is based in ESA is Europe’s gateway to space, with its headquarters in Paris, Cambridge, UK. To learn more, see: www.embl.org France. For more information, see: www.esa.int For a list of EMBL-related articles in Science in School, see: For a list of ESA-related articles in Science in School, see: www.scienceinschool.org/embl www.scienceinschool.org/esa www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 3 ESO: ESRF: Sweet discovery in space Hot ice in Neptune Astronomers using ALMA, one of the world’s largest ground-based astronomy projects, have spotted molecules of glycolaldehyde – a simple form of sugar – around a young binary star with similar mass to the Sun, called IRAS 16923-

2422. Glycolaldehyde (C2H4O2) has been seen in interstellar

space before, but this is the first time it has been found so Neptune and Triton. pp. 109-138. Tucson, AZ, USA: University of Arizona Press. ISBN 978-0816515257 Image courtesy of Sandra Ninet; image of Neptune by NASA / JPL-Caltech; model adapted from Hubbard WB, Podolak M, Stevenson DJ (1995) The Interior of Neptune. In Cruikshank DP (ed) near to a Sun-like star. The molecule is one of the ingredients in the formation of RNA, which – like DNA, to which it is similar – is one of the building blocks of life. The discovery shows that these building blocks are in the right place, at the right time, to be included in planets forming around the star. For more information, see the press release: www.eso.org/public/ news/eso1234 To learn more about ALMA, see: Image courtesy of ALMA (ESO / NAOJ / NRAO) / L Calçada (ESO) & NASA / JPL-Caltech / WISE Team Mignone C, Pierce-Price D (2010) The ALMA observatory: the sky is only one step away. Science in School 15: 44-49. www. Neptune’s main constituents are water (H O), ammonia (NH ) and scienceinschool.org/2010/issue15/alma 2 3 methane (CH4) ices. The core may be composed of rocks and ice; the The European Southern Observatory (ESO) is by far the world’s outside layer is formed mainly by helium, hydrogen and methane. most productive ground-based astronomical observatory, with its headquarters in Garching near Munich, Germany, and its telescopes in Chile. ESO is the European partner in the ALMA The main constituents of the planets Neptune and Uranus project, which is a collaboration between Europe, North Ameri- are water, ammonia and methane in solid phases called ‘ices’. ca and East Asia, in co-operation with the Republic of Chile. For more information, see: www.eso.org They are very different from ice on Earth, though: up to 5000 For a list of ESO-related articles in Science in School, see: K hot and under extreme pressures of several million atmos- www.scienceinschool.org/eso pheres. Under such conditions, scientists have predicted the existence of a new state of ammonia ice, called superionic ammonia. Superionicity is an exotic state of matter that behaves The Rho Ophiuchi star-forming region seen in infrared light. IRAS 16293-2422 is the red object in the simultaneously as a crystal (fixed ion lattice) and as a liquid centre of the small square. Inset: an artist’s impres- (diffusive ions). sion of glycolaldehyde molecules, the form of sugar Now scientists have confirmed the existence of superionic that has been found around IRAS 16293-2422. ammonia experimentally at the European Synchrotron Radia- tion Facility (ESRF): they submitted an ammonia sample to very high pressure while heating it, and followed its phase transformations using intense X-rays. Unexpectedly, however, they detected superionic ammonia at a lower temperature than predicted: 750 K instead of 1200 K. The exact boundaries of this superionic phase are crucial, because they determine whether it could exist in Neptune and Uranus. Therefore, the scientists will next test whether superionic ammonia is stable under even higher temperatures and pressures. Should this be the case, it could help explain the origin of the planets’ magnetic fields, which are not yet well understood. To learn more, see the news item on the ESRF website (www.esrf. eu), use the direct link (http://tinyurl.com/superionic), or read the research paper: Ninet S, Datchi F, Saitta AM (2012) Proton disorder and superionicity in hot dense ammonia ice. Physical Review Letters 108(16): 165702-1–165702-5. doi: 10.1103/PhysRevLett.108.165702 Situated in Grenoble, France, ESRF operates the most powerful synchrotron radiation source in Europe. To learn more, see: www.esrf.eu For a list of ESRF-related articles in Science in School, see: www.scienceinschool.org/esrf

4 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Biology Chemistry Physics 5

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read link (http://tinyurl.com/hbevolution),or direct the use eu), paper: the research AM et al. (2012) Thermal fluctuations of haemoglobin Stadler via conforma species: adaptation to temperature different from tional dynamics. Journal of the Royal Society 9(76): 2845-2855. doi: 10.1098/rsif.2012.0364 science tron see: www.ill.eu more, www.scienceinschool.org/ill /

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e as an oxygen ent species has evolved to perform its function at that species’ body temperature. carrier very effectively composition of this They found variations in the amino-acid found in all vertebrates, that affect which is protein, iron-rich and thus its ability to softness and flexibility, the protein’s withstand warmer or cooler temperatures. a range of vertebrates. The team studied haemoglobin from lowest body The duck-billed platypus, at 33 °C, has the of all endotherms (vertebrates that maintain temperature such as mammals or birds). a constant body temperature, Humans, at 36.6 °C, have an intermediate body temperature, tend the chicken, at 41 °C, is as hot-blooded as birds whereas to be. The scientists also studied the ectothermic saltwater by that is regulated – which has a body temperature crocodile varying between 25 and 34 °C. the environment, between the resilience correlation The scientists found a direct of the spe- of haemoglobin and the average body temperature each species’ which it was sampled. In other words, cies from haemoglobin appears to have evolved to unfold at exactly the right body temperature. Using the facilities at the Institut Laue-Langevin (ILL), a Using the facilities at the Institut Laue-Langevin in differ team of biologists have shown that haemoglobin website (www.ill. on the ILL release see the press learn more, To ILL: and Cold-blooded platypus hot-blooded chicken at the leading edge of neu- centre is an international research ILL articles in Science in School For a list of ILL-related

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u y r s t e Tuning the pole Tuning heights of an the undulator in - magnetic measure ment laboratory. page 65. To learn how to learn how To use this code, see articles relating to European XFEL, see: to European articles relating ) times that of an ordinary 60 W light ) times that of an ordinary 24 www.scienceinschool.org/xfel in the Hamburg area in Germa- area in the Hamburg under construction ity currently by researchers intense X-ray flashes will be used Its extremely ny. see: www.xfel.eu learn more, all over the world. To from EIROforum combines the resources, facilities and EIROforum combines the resources, expertise of its member organisations to support To its full potential. European science in reaching learn more, see: www.eiroforum.org a list of EIROforum-related articles in Science in For , see: www.scienceinschool.org/eiroforum School the other EIRO news articles, see: browse To www.scienceinschool.org/eironews bulb, making the new research facility the brightest light bulb, making the new research on Earth. Deliveries of the devices generating this source undulators – to the site in Hamburg – the firework incredible The magnetic have been taking place since October 2012. electrons accelerated of the undulators will force structures X-ray flashes of onto a slalom course, inducing them to emit quality. extraordinary undulator systems, with the The new facility will have three ones each 212 m long. They consist of segments two larger in close collaboration with European that have been produced installed, the undulator group the segments are XFEL. Before and tune their will extensively measure XFEL of European will eventually be The light they produce magnetic properties. to film ultrafast used, for example, to examine biomolecules, conditions. and to study matter under extreme processes EIROforum European X-ray Free Electron Layer (XFEL) is a research facil- Layer (XFEL) is a research Electron X-ray Free The European For a list of Science in School The European XFEL will deliver up to 27 000 very intense XFEL The European than more X-ray light flashes per second with a brightness 100 septillion (100 x 10 European XFEL: brightest light source The on Earth www.scienceinschool.org

Image courtesy of European XFEL CERN y of rtes ou e c ag Rolf Heuer Im Accelerating the pace of science: interview with CERN’s Rolf Heuer

By Eleanor Hayes ers to the senior management – we Heuer explains, “It’s also one of the all identify ourselves with CERN, coldest places in the Universe, cooled CERN is not just the world’s larg- sharing a desire to increase human to 1.9 K with superfluid helium. Even est particle physics laboratory. As its knowledge. We all do our bit towards outer space is warmer, at 2.7 K. director general, Rolf Heuer, explains, that goal, leaving political, cultural “Simultaneously, it’s one of the “CERN is a role model, demonstrat- and educational differences outside hottest places in our galaxy because ing that science can bridge cultures the campus.” when we collide protons in the LHC, and nations. Science is a universal This undoubtedly makes CERN a we produce temperatures that are language and this is what we speak at very special place to work, but what much, much higher than those at the CERN.” makes it unique is its particle accelera- centre of the Sun.” Professor Heuer CERN also unites people in other tor, the Large Hadron Collider (LHC). describes the collision of two protons ways. “As a young summer student, First used in 2008, the LHC is the you can find yourself having lunch world’s largest particle accelerator, its Part of the 27 km tunnel that houses next to a Nobel Prize winner. And 27 km tunnel forming a ring beneath the LHC. To allow for the necessary everyone, from the canteen work- the French-Swiss border. As Professor measurements on the new particle, the LHC will run until February 2013. Professor Heuer explains: “Imagine you see someone a long way away who looks like your best friend. To be certain that it is not actually his or her twin, you need to wait until you’re close enough. That takes time.” I mage cou rte sy of CE RN

6 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Image courtesy of CERN Physics 7 I

- tells us that to create tells us that to create 2 Issue 25 : Winter 2012 Winter Issue 25 : I

Feature articleFeature hool As Professor Heuer and I talk, ex- Heuer and I talk, As Professor Science in Sc getic collisions can create very heavy very getic collisions can create particles, the sort of particles that ener formed in the extremely were getic conditions a fraction of a second particles after the Big Bang. These are so massive that they have not been that Ein- then (remember since created stein’s law E=mc a very heavy particle, we need a large a very heavy particle, we need a large amount of energy). has just been distant history tremely

m : The 1: The Figure standard model describes the fundamental particles we, and from which visible thing in every made, are the Universe, acting and the forces between them. I As detailed in two previous Science previous As detailed in two at close to the speed of light as being the speed of light at close to colliding in mid- like two mosquitoes these is that flight. “The key difference tiny particles, so tiny, tiny, are protons of density – the energy their energy divided by their volume the protons density this energy – is huge, and it is to the Big Bang.” that brings us close Rau, 2008; in School articles (Landua & enormously ener Landua, 2008), these Higgs boson 2 Force particles Force (bosons) - Pe Leptons

ter Higgs was ter Higgs was

described by Professor described by physics.” Heuer as “very moved by by moved Heuer as “very have understood particle have the announcement. He said no longer existence, he would that if we had excluded the possibility of the Higgs boson’s Quarks Peter Higgs Peter E=mc Einstein’s iconic equation tells us that iconic equation Einstein’s particles that heavy to create the very after the of a second existed a fraction to collide Big Bang, the LHC needs high energies. particles at very Image courtesy of CERN www.scienceinschool.org Image courtesy of Nicola Graf Image courtesy of CERN

Figure 2: The Higgs mechanism

re-enacted: on 4 July 2012, CERN an- mental particles from which we and by interacting with this field; the more nounced the detection by the LHC of every visible thing in the Universe the particles interacted with the Higgs a particle that is ‘consistent with the are made, and the forces acting be- field, the more massive they became. Higgs boson’, last created about tween them. And as Professor Heuer “Imagine that the Higgs field is a 10-12 seconds after the Big Bang. This is explains, “The Higgs boson was the party of journalists, equally distrib- momentous news. “We’ve been look- missing cornerstone of the standard uted in the room,” says Professor ing for this particle for 40 years. I’m model.” Heuer. “I can pass through the room not sure if I’ve digested the news yet, The discovery would also explain mass-less – with the velocity of light but I think this might be one of the why particles – and thus matter – – because they don’t know me. If biggest discoveries of recent decades,” have mass. The search for the Higgs someone well known enters, the jour- he tells me. boson began in the 1960s, when a nalists cluster around that person: the If the newly detected particle is in- group of physicists, including Peter person’s velocity is limited and he or deed the Higgs boson, this discovery Higgs, postulated what is now known she acquires mass. The better known will validate the standard model of as the Higgs field. Immediately after that person is, the more the journalists particle physics. The standard model the Big Bang, they believed, particles cluster around, and the more massive (figure 1, page 7) describes the funda- had no mass but rapidly acquired it that person becomes. This is how a

8 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Feature article

Images courtesy of CERN

2000 3500 1800

3000 1600 1400 2500 1200 2000 1000 1500 800 600 1000 400 500 200 Weighted number of decays detected number of decays Weighted Weighted number of decays detected number of decays Weighted 0 100 110 120 130 140 150 160 120 140 Mass of decayed particle (GeV) Mass of decayed particle (GeV)

Results obtained from the ATLAS (left) and CMS (right) experiments, showing the (weighted) number of decays detected at

each particle mass. The gap between the dotted and solid red lines shows the deviation from the expected results, representing Physics the decay of the new particle.

particle acquires mass from the Higgs particles, but there was still no sign of One promising signal to look for field.” See figure 2, page 8. the Higgs boson. Did it not exist after was the decay of the Higgs boson into But where does the Higgs boson all, or did it just require a still more two photons, specifically two high-en- come in? By definition, bosons are powerful accelerator to detect it? The ergy photons. When two photons are particles with an internal angular new particle may well have answered detected originating from the same momentum – known as spin – corre- that question. spot, they may be the result of a Higgs sponding to an integer multiple of the So how did the CERN scientists boson decaying. On the other hand, Planck constant (e.g. 0, 1 or 2). Some actually detect this new particle? The bosons are force particles, through signal they were looking for was the which matter particles interact with decay of the Higgs boson. However, A computer-generated image of data each other. For example, a photon is a the scientists needed to be able to from one of the many collisions that was used to search for the Higgs boson that carries the electromagnetic distinguish the decay pattern of the boson. “It’s not looking for a needle force; a graviton is a boson that car- Higgs boson from the decay signals in a haystack: this is looking for a ries the gravitational force. The Higgs of the many, many other particles cre- needle in millions of haystacks, with boson, however, is postulated to be ated in the LHC. As Professor Heuer the slight problem that the haystacks different: it is the result of the Higgs jokes, “It’s like looking for one type also consist of needles and we have field interacting with itself (figure 2, of snowflake by taking photos of it to find one needle with a very slight Image courtesy of CERN page 8). “Suppose I open the door to against a background of a snowstorm. difference from in among many, many other needles,” Professor the journalists’ party and whisper a Very difficult.” Heuer explains. rumour into the room. The journalists will be curious – ‘what did he say?’ That’s the journalists interacting among themselves – or the self- interaction of the Higgs field: that is a Higgs boson.” The only problem with the Higgs boson was that nobody knew if it actually existed. Over the years, larger and larger particle accelerators have been built to look for it, capable of colliding particles with higher and higher energies. This enabled physicists to create more and more massive

Science in School I Issue 25 : Winter 2012 I 9 www.scienceinschool.org - Image courtesy of ARTPUPPY / iStockphoto - - www.scienceinschool.org It’s also important to measure the It’s also important to measure - is to meas The next step, therefore, the force “If you swim in a river, pend on which direction you swim you pend on which direction in. That would be a vector field. If, in pool, in a swimming contrast, you are on you that the water exerts the force will be the same whichever direction you swim in. That’s a scalar field.” accurately. new particle’s mass more “Instead of being the Higgs boson, it could be a Higgs boson. The standard super only one, but model predicts - symmetry – an extension of the stand model (as explained in Landua ard at least five. & Rau, 2008) – predicts And the lowest-mass Higgs boson by supersymmetry is very predicted by similar in mass to that predicted model. That makes it dif the standard ficult to distinguish the two; we need cautious. As a layman, I would say a layman, I would As cautious. As a boson’. ‘we’ve found the Higgs ask ‘what have we scientist, I have to found?’” in- of this particle, the properties ure known All previously cluding its spin. particles with spin 1, for bosons are associated are example photons. They the electromagnetic with vector fields: is a vector field that field, for instance, and a strength. has both a direction in a the photon is moved As a result, The it has spin. particular direction: is postulated Higgs boson, however, – it is associated with a to be different scalar field, the Higgs field, and that means it has spin 0. that the water exerts on you will de - mid-flight. mosquitoes colliding in the LHC as being like two the LHC as being like two Professor Heuer describes the collision of particles in . w1 The initial data in July 2011 cer 2011 The initial data in July For most of us, despite previous So how much do we actually know tainly looked promising, but offered but offered tainly looked promising, near this level of certainty. nowhere the however, year, Over the following more gathered two LHC experiments in the data, all pointing and more two- more were there same direction: photon events with a mass of 126 GeV were than would be expected if there on 4 July no Higgs boson. Finally, was 2012, the five-sigma threshold were and the CERN scientists crossed confident enough to announce to the world that they had indeed detected ‘a particle consistent with the Higgs boson’. CERN, this tentative statements from announcement came quite unexpect- in contrast, Heuer, For Professor edly. the excitement had been building up - over months, but the step-by-step rev elation of the discovery did not reduce its impact one bit. “The discovery is the most exciting moment of my ca- writing a little bit because we are reer, of history.” know about this new particle? “We it’s a new particle and we know it’s a boson. It’s the heaviest boson ever found, and it looks like the Higgs bo- scientists can be very son. However, cal significance is set very high: at is set very high: cal significance a about five sigma, which represents of detecting one in 3.5 million chance than expected by chance decays more hypothesis were alone, even if the null true

Image courtesy of CERN Image courtesy Issue 25 : Winter 2012 Winter Issue 25 : I number of decays de Science in School Science in School I This was precisely what two of the what two This was precisely The answer is that they cannot, in The answer is that tected is what they would expect. For tected is what they would expect. For a null hypothesis this, they construct – in this case, that the Higgs particle what they does not exist – and predict would find if the null hypothesis were detected decays were If more true. than expected, this would indicate the existence of the Higgs boson. and CMS, ATLAS LHC experiments, above the smooth found in July 2011: there curve of the expected results, more was a deviation representing decays than expected. Importantly, both experiments found this deviation the at the same point – representing decay of particles with a mass of 126 GeV – and the deviation had the same magnitude – representing the same number of ‘extra’ decays The question was, in the accelerator. these deviations statistically were significant? For new discoveries in particle physics, the bar for statisti- they may be part of the background the background they may be part of collisions and noise of other particle the LHC. So how decays occurring in the two? do the scientists distinguish the photons any one case, tell whether or from a Higgs boson originate from the decay of some other particle, but they can use statistical analysis to test whether the 10 Physics 11 I

Image courtesy of CERN ”. Professor Heuer is ”. Professor Issue 25 : Winter 2012 Winter Issue 25 : I Feature articleFeature

-century mechanics, you th As we close our interview, I ask As we close our interview, Throughout our interview, it’s our interview, Throughout Heuer as Professor The difficulty, will lose 99% of them immediately. will lose 99% of them immediately. modern science, however, Introducing he is help.” Fortunately, can really convinced that a lot can be explained clearly a fan. further Heuer has any if Professor “Enthusing advice for our readers. school students within the current – if you curricula can be very difficult start with 19 sentially nothing about dark energy, energy, about dark sentially nothing the LHC, we are but I think that, with Universe.” about to enter the dark - much Profes been obvious just how bringing physics sor Heuer relishes He’s clearly alive for non-specialists. “I gave a public very good at it, too: the Royal Society in London in lecture the LHC, the in which I presented it and the fascination science around I day later, A of the dark Universe. a 14-year-old an email from received very doing that he was wrote boy who well in maths and physics and that he wanted to start work at CERN in 2018.” young acknowledges, is not rousing people’s enthusiasm for science, but this end, he empha- maintaining it. To sises the importance of “explaining new developments and important topics in science, for example using Science in School Science in School Science in School This map compares the map compares the This distribution of ‘normal’ gas, via hot traced matter, the space telescope seen by and XMM-Newton (in red) stars and galaxies observed with the Hubble Space (in grey), to the Telescope distribution of the invisible which dark matter (in blue), the has been inferred from lensing effect. gravitational map demonstrates The ‘normal’ matter across how the follows the Universe structure of an underlying ‘scaffolding’ of dark matter. Of the dark 95% of the Universe quarters of the dark The other three we know very little In short, “So far, the faintest light on what dark matter the faintest light on what dark matter is.” or dark energy standard by the that is not addressed - model, 25% is thought to be dark mat that to the 5% we compare “When ter. that comprises the visible Universe, it’s obvious that dark matter must in shap- have played a dominant role Astronomers ing the early Universe. can tell us how it has shaped the Uni- verse, but only particle accelerators dark likely to be able to produce are matter in the laboratory and help us understand exactly what it is. Is dark matter composed of a single kind of particle or is it rich and varied like the normal world?” One potential and answer involves supersymmetry, the LHC will be after refurbishment, and detect powerful enough to create some of the very massive particles that supersymmetry would predict. thought to Universe is dark energy, drive the Universe apart. Professor Heuer believes that the LHC and its investigation of the Higgs boson could too. “The Higgs be important here They as is dark energy. field is scalar, not the same, but studying the are Higgs field might tell us a lot about dark energy.” about dark matter and we know es- - - - - So if the measurements over the over So if the measurements Whatever the outcome of the meas- more measurements.” To this end, the To measurements.” more as many LHC will collect data from collision events as possible before 2013, when it will be closed February it for still until the end of 2014 to refit enabling collisions, higher energy heavier and detect even it to create particles. next few months show the new particle to be the (or a) Higgs boson, then be validat model would the standard the Higgs the existence of ed, proving field, and thus confirming the mecha mass. nism by which particles acquire bo- But what if the newly discovered son turns out not to be a Higgs boson? to what we “If it’s slightly different physics expected, it could introduce model.” beyond the standard on the new particle, once urements it will turn its the LHC is reopened, model, focus beyond the standard which describes only the visible Uni- than verse – thought to be no more balance of the 4-5% of the total energy Heuer points As Professor Universe. model leaves out, “The standard many questions open. For example, it doesn’t tell us what happened to the antimatter that existed at the begin ning of the Universe, nor does it tell us in how many space or time dimen And it casts not living. sions we are Image courtesy of NASA / ESA / R Massey (California Institute of Technology) Institute of / ESA / R Massey (California of NASA Image courtesy www.scienceinschool.org Image courtesy of CERN

on 14 July 2012, just 10 days after the announcement that a boson compatible with the Higgs boson The CERN control room had been discovered at CERN. See: www.livestream.com/esof2012 or use the direct link: http://tinyurl. com/95xmwf2 To learn more about the next genera- tion of particle accelerators that will study the Higgs boson in more detail, see: Chalmers M (2012) After the Higgs: Resources the new particle landscape. Nature To learn more about the LHC shut- 488: 572-575. doi:10.1038/488572a without mathematics. “For example, down, planned for 2013-14, see: Download the article free of charge I explained the Higgs mechanism by Brewster S (2012) Scientists already on the Science in School website talking about journalists. Of course, planning for LHC long shutdown. (www.scienceinschool.org/2012/ to fully understand it and explain Symmetry September 2012. www. issue25/heuer#resources), or sub- it, your students would need to use symmetrymagazine.org or via scribe to Nature today: www.nature. mathematics, but they can always the direct link: http://tinyurl. com/subscribe look that up. What they need to un- com/9oo3erw derstand is the logic.” To learn more about the research References leading to the discovery of the new Dr Eleanor Hayes is the editor-in- particle, see: chief of Science in School. She studied Boffin H (2008) “Intelligence is of zoology at the University of Oxford, secondary importance in research”. Baggott J (2012) Higgs: The inven- UK, and completed a PhD in insect Science in School 10: 14-19. www. tion and discovery of the ‘God Parti- ecology. She then spent some time scienceinschool.org/2008/issue10/ cle’. Oxford, UK: Oxford University working in university administration tamaradavis Press. ISBN: 9780199603497 before moving to Germany and into Landua, R (2008) The LHC: a look For an explanation of the LHC in layperson’s terms, see: science publishing in 2001. In 2005, inside. Science in School 10: 34-45. she moved to the European Molecular Ginter P, Franzobel, Heuer RD www.scienceinschool.org/2008/ Biology Laboratory to launch Science (2011) LHC: Large Hadron Collider. issue10/lhchow in School. Landua R, Rau M (2008) The LHC – Paris, France: UNESCO. a step closer to the Big Bang. ISBN: 9783901753282 Science in School 10: 26-33. Watch Rolf Heuer’s lecture ‘The To learn how to use www.scienceinschool.org/2008/ search for a deeper understand- this code, see page 65. issue10/lhcwhy ing of our Universe at the Large Warmbein B (2007) Making dark mat- Hadron Collider: the world’s largest ter a little brighter. Science in School particle accelerator’, given at the Euroscience Open Forum in Dublin, 5: 78-80. www.scienceinschool. Im age co urtes org/2007/issue5/jennylist y of CE RN Web reference w1 – To find out more about the statistical analysis, see ‘5 sigma – what’s that?’ in the Scientific American blog. See: http://blogs. scientificamerican.com (search for ‘5 sigma’) or use the direct link: http://tinyurl.com/5sigmap

12 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Cutting-edge science Biology Sloppy fishing: Biology Cytology when meiosis Genetics Reproduction Ages 15+ goes wrong This article is about new scientific inputs concerning the understanding of cell divi- Why does meiosis so sion mechanisms, namely the attachment of microtu- often go wrong? bules to chromosomes dur- And what are the ing mitosis and meiosis. The level of detail in this arti- consequences? cle makes it particularly useful for upper-secondary biology classes (ages 15+), for Image courtesy of QUOI Media; image source: Flickr topics such as cytology (mitosis and meiosis), genetics (the causes and implications of chromosomal abnormalities) and reproduction (ga- metogenesis and infertility). The article can also be used to initiate wider discussions about both the benefits of modelling biological phe- nomena (models can help us to understand processes) and the risks. For example, in the majority of text-books describing mitosis and meio- Fishing with magnets sis, chromosomes are rep- resented as large structures. This can lead students to be- By Sonia Furtado Neves, EMBL Laboratory (EMBL; see box on page lieve that chromosomes are 15) have found, is that magnet-wield- easily observable in any type t a village fair, past the ing children are probably more suc- of cells. As is clear from the bumper cars and candy- cessful fishermen than the egg cell’s article, however, this is not the case. Im floss, a child’s forehead machinery (Kitajima et al., 2011). age co urtes y of CE creases in concentration. He’s doing As an egg cell, or oocyte, matures Finally, the article illustrates RN A his best to snag a wooden fish out of inside a woman’s ovary, it undergoes how the efforts made in one a plastic pond, using the magnet on a type of cell division called meiosis, research group might benefit the end of his fishing rod. Freeze the in which the pairs of chromosomes other research areas, as well scene, rewind all the way through the inside it are lined up and fished apart, as highlighting the synergis- child’s development, past the point and half of them are expelled. The tic relationship between sci- when the sperm fertilised the egg, to chromosomes are brought together ence and technology. when the egg cell itself was formed, from all over the cell (Mori et al., Betina da Silva Lopes, and you’ll find a similar fishing game 2011) and fished apart by protein rods Portugal in action. The difference, as scientists called microtubules. Like the child’s REVIEW at the European Molecular Biology rod pulling a toy fish by its magnet, a

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 13 Image courtesy of Tryphon; image source: Wikimedia Commons

The main events of meiosis during during crossing over. Meiosis is then cell maturation. A: During the first halted until ovulation, and most of five months of development of a the potential egg cells die off again. female human embryo, all its po- B: Between puberty and meno- tential future egg cells are formed. pause, during each monthly cycle, Diagram of a chromosome. The In each of these cells, after DNA a few potential egg cells progress centromere (red dot) is the site of duplication, homologous chromo- further during the stages of meiosis, assembly of the kinetochore. somes exchange genetic material but only one at a time eventually

microtubule catches a chromosome by to keep track of all the kinetochores which allowed him to programme a its kinetochore – a cluster of protein throughout cell division – so there’s laser scanning microscope to find the and genetic material at the centre of not a single time point where it’s am- chromosomes in the egg cell’s vast the chromosome’s X shape. biguous where that part of the chro- inner space, and then film them dur- By examining mouse egg cells un- mosome is – and that’s really a breaking cell division. “The oocyte is a big der the microscope, EMBL scientist through in the field, achieving this in cell, but the chromosomes sit in only a Tomoya (Tomo) Kitajima was the these very large and light-sensitive small part of that cell, and that’s what first to track the movements of all of cells,” says Jan Ellenberg, who heads we were interested in. So basically an egg cell’s kinetochores during the the research group. we just made our microscopes smart whole of cell division – all 10 hours Tomo used software that had been enough that they can recognise where of it. “We were able, for the first time, previously developed in Jan’s lab, the chromosomes are and then zoom

Mapping movement: the coloured Cheating microtubules: before they Chromosomes (blue) lined up in lines chart the movement (purple to start attaching themselves to kineto- preparation for separation. Kineto- yellow) of kinetochores (green dots) chores (green), microtubules nudge chores (red) attach chromosomes as microtubules hook onto them to chromosomes (red) into a ring to the cell’s microtubules (green). separate the chromosomes (cyan). around the centre of the spindle. Images courtesy of Tomoya Kitajima, EMBL

14 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Cutting-edge science

Image courtesy of Nicola Graf Biology

completes the process. Homologous egg cell, and at the time of ovulation, mature egg cell, and meiosis is complete. chromosomes line up at the primary egg microtubules attach to them. Meiosis is Each of the four resulting daughter cells cell’s equator and are then fished apart arrested here until fertilisation. has a different genetic makeup. by microtubules. The primary egg cell C: If fertilisation happens, the paired The genetic material of the polar bodies divides into a secondary egg cell and a chromatids are pulled apart, moving to is discarded, while that of the mature egg polar body. opposite poles of the cells. The polar cell is joined by the genetic material of Now paired chromatids line up at the body divides in two, the secondary egg the fertilising sperm, to start the develop- equators of both the polar body and the cell divides into a third polar body and a ment of a new embryo. in, in space and time, just on that re- sion (for more on smart microscopy, nudge chromosomes into a favourable gion,” Jan explains. By focusing the see box on page 17). position, like a child repositioning a microscope only on the part of the cell Back at the fishing pond, tempers fish with the end of his rod. The mi- where the chromosomes are, Tomo can flare and voices rise in shrill ac- crotubules nudge the chromosome was able to obtain high-resolution im- cusation: “That’s cheating! You can’t arms, arranging the chromosomes in ages at short intervals of only one and push the fish with your rod!” Thanks a ring from which they can then fish a half minutes, which gave him a very to Jan and Tomo’s work, the accused them out more easily. clear picture of the process. And, be- child could argue, in his defence, that “But even with this pre-positioning, cause the microscope was only firing his cells were already ‘cheating’ like it still doesn’t work very well,” says light at that small region of the oocyte, this before he was even born. When Jan. “We saw that 90 % of kinetochore it did less damage to the cell, which the EMBL scientists analysed the connections were initially wrongly es- enabled the scientists to keep up the videos, they found that, before micro- tablished, and the microtubules had to imaging for the 10 hours of cell divi- tubules attach to kinetochores, they release the chromosome and try again – on average, this had to be done three times per chromosome.” Scientists in the USA have now More about EMBL shown that the same ‘cheating’ also happens in the other type of cell division, which our cells undergo when The European Molecular Biology we grow or when tissues such as skin Laboratory (EMBL)w1 is one of the world’s regenerate (Magidson et al., 2011). In top research institutions, dedicated to basic this second type of cell division, called research in the life sciences. EMBL is international, innovative and interdis- mitosis, a cell divides into two daugh- ciplinary. Its employees from 60 nations have backgrounds including biology, ter cells, each with the same amount physics, chemistry and computer science, and collaborate on research that of genetic material as the ‘mother cell’, covers the full spectrum of molecular biology. instead of half the genetic material as in meiosis. But Jan and Tomo’s find- EMBL is a member of EIROforumw2, the publisher of Science in School. ings highlight that the fishing of chro- Read all EMBL-related articles in Science in School: mosomes involves much more error in www.scienceinschool.org/embl the egg cell’s meiosis than in mitosis. The greater degree of error in meiosis www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 15 Images courtesy of ericskiff; image source: Flickr

could, the scientists believe, be due to to make the right connections to sepa- References a fundamental difference in how mi- rate chromosomes properly, Tomo and Kitajima TS, Ohsugi M, Ellenberg J crotubules fish chromosomes apart in Jan have provided a focus for future (2011) Complete kinetochore track- the two types of cell division. studies. In fact, Tomo is now going ing reveals error-prone homologous During mitosis, the microtubule on to study why this trial-and-error chromosome biorientation in mam- rods start forming at two opposite process is even more error-prone in malian oocytes. Cell 146(4): 568-81. points in the cell and come together older egg cells. If he and others can doi: 10.1016/j.cell.2011.07.031 in a lemon-shaped structure – the pinpoint where the error-correction Magidson V et al. (2011) The spatial spindle – that then pulls each chromo- mechanisms fail in older cells, it could arrangement of chromosomes dur- some in a pair to one side, or pole. But one day be a starting point for medical ing prometaphase facilitates spindle in meiosis, as Jan’s group discovered procedures to help microtubules im- assembly. Cell 146(4): 555-67. doi: a few years ago (Schuh & Ellenberg, prove their fishing technique. Perhaps 10.1016/j.cell.2011.07.012 2007), the spindle’s microtubules con- the secret to countering age-related verge from as many as 80 different infertility is to make microtubules as Mori M et al. (2011) Intracellular points at first, and only later arrange successful at fishing as children are transport by an anchored homoge- themselves into a two-poled struc- with their toy magnets. neously contracting F-actin mesh- ture. “So when microtubules are first work. Current Biology 21: 606-61. doi: attaching to chromosomes, it’s hard 10.1016/j.cub.2011.03.002 to know if they’re going to end up pulling them in opposite directions Image courtesy of Mysid; image source: Wikimedia Commons or not,” Jan explains. This, along with the fact that the egg cell is a much larger expanse across which microtubules have to find and drag chromosomes – a human egg cell is more than four times larger than a skin Two diploid cells cell – could explain why chromosome fishing is so much more error-prone in egg-cell division. These findings also provide scien- Mitosis tists with a more concrete place to look when studying female infertility and conditions like Down syndrome, which largely stem from egg cells with Mitosis: after the cell has replicated its DNA, the chromosomes line up at the an abnormal number of chromosomes. cell’s equator. Microtubules attach to the kinetochores of sister chromatids and By showing that such errors most fish them apart. After mitosis, the cell divides. The two resulting daughter cells likely occur because microtubules fail are genetically identical to the parent cell.

16 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Biology Image courtesy of QUOI Media; image source: Flickr 17 - I

Issue 25 : Winter 2012 Winter Issue 25 : I

To learn how to use learn how To this code, see page 65. Cutting-edgescience why not browse the other cutting- the other why not browse in Science in articles edge research School? www.scienceinschool.org/ cuttingedge Sonia Furtado Neves was born in If you found this article interesting, If you found this article interesting, London, UK, and moved to Portugal While studying for at the age of three. in zoology at the University a degree of Lisbon, she worked at Lisbon Zoo’s she dis- education department; there, enjoys is that what she really covered telling people about science. She went on to do a master’s in science degree communication at Imperial College officer London, and is now the press Molecular Biology at the European Germany. Laboratory in Heidelberg, Science in School Science in School

ticular biological process. Making microscopes smarterMaking microscopes through- used to find and film chromosomes Tomo that software The to come. Since then, in col- a prelude of things was out cell division Jan’s Pepperkok, Rainer at EMBL led by with another team laboration even of capable programme, complex more a developed has group anal- Called Micropilot, the new software greater feats of automation. finds not just a microscope and taken by images yses low-resolution has taught it to look structure the scientist but whatever chromosomes for. or structure that the scientists Once Micropilot has identified the cell the microscope to start an are interested in, it automatically instructs can be as simple as recording high-resolution time- This experiment. fluores- with interfere lasers to as using as complex lapse videos or a is software The results. the recording and proteins tagged cently more data at a faster generates boon to systems biology studies, as it high throughput, Micropilot can easily and quickly to its Thanks pace. enough data to obtain statistically reliable results, allowing generate of different proteins in a par scientists to probe the role of hundreds BACKGROUND ing the chromosomes into position. ing the chromosomes See: http://youtu.be/LH9wI7_B-4g EMBL, see the EMBL website: website: EMBL, see the EMBL www.embl.org in- largest between eight of Europe’s scientific research ter-governmental which combine their organisations, facilities and expertise resources, science in to support European As part of its full potential. reaching activi- its education and outreach publishes Science ties, EIROforum see: www. learn more, in School. To eiroforum.org Resources nudg- a video of microtubules Watch Web references Web about information w1 – For more is a collaboration w2 – EIROforum - - - - - Bumper cars Cell 130(3): 484-98. A freely available and simply writ- freely A ten explanation of this research annual is available in the EMBL report: In (2012) Neat nets. EMBL Annual Report 2011/2012 EMBL Ger pp 86-88. Heidelberg, Biol Molecular many: European www.embl.de/ ogy Laboratory. aboutus/communication_outreach/ publications replaces of MTOCs organization acen function during centrosome in live spindle assembly trosomal mouse oocytes. doi: 10.1016/j.cell.2007.06.025 available and simply writ- freely A ten explanation of this research annual is available in the EMBL report: (2008) Push me, pull you. EMBL Annual Report 2007/2008 In EMBL Ger pp 46-50. Heidelberg, Molecular Biol many: European www.embl.de/ ogy Laboratory. aboutus/communication_outreach/ publications Self- J (2007) Schuh M, Ellenberg

Image courtesy of D Petzold Photography; image source: image source: Photography; of D Petzold Image courtesy Flickr www.scienceinschool.org The numbers game: extending the periodic table

Image courtesy of Jim Mikulak; image source: Wikimedia Commons Public domain image; image source: Wikimedia Commons Wikimedia source: image image; domain Public Until a few centuries ago, people believed that the world was made only of earth, air, water and fire. Since then, scientists have discovered 118 elements and the search is on for element 119. Mendeleevs’s periodic table, published in 1869

By Oli Usher

scopic variety, elements are pretty * * * n space-age labs across Europe, simple, and there are so far only 118 The Russian chemist Dmitri Men- researchers are working together elements known to sciencew1. Discov- deleev knew none of this when, in to discover new elements. If ering a new one is a big deal. 1869, he arranged the elements into theyI succeed, they will join the club Atoms, the building blocks of mat- a table based on their atomic weight. of scientists who have rewritten the ter, are all made of the same simple He quickly saw patterns emerge: in periodic table. components: tiny particles called particular, columns grouped together The Ancient Greeks might not have protons and neutrons, and even tinier elements with startlingly similar prop- been right about there being just four electrons orbiting them. The number erties. For example, potassium, ru- elements – earth, air, fire and wa- of protons in an atom – its atomic bidium and caesium, three metals that ter – but they were onto something: number – defines what element it is. react violently with water, are stacked elements are the ingredients of eve- An atom of oxygen, for example, has one above the other. rything that surrounds us, bound to eight protons, eight neutrons (usu- At first, Mendeleev’s table had a each other in compounds and mixed ally) and eight electrons, whereas the problem: it was full of gaps. Between together in different proportions. But heaviest elements can have more than zinc and arsenic, for instance, there while compounds exist in kaleido- a hundred of each. seemed to be two elements missing.

18 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Cutting-edge science

Public domain image; image source: Wikimedia Commons Image courtesy of Halfdan; image source: Wikimedia Commons Image courtesy of Jim Mikulak; image source: Wikimedia Commons Chemistry

Dmitri Mendeleev Lithium

But he boldly predicted that these arranged in their orbits in different a trickle of new lab-created elements holes would be filled with newly dis- elements, and the electrons in turn dic- started to join the end of the periodic covered elements, and used his table tate many of the elements’ properties. table, bringing us up to the 118 ele- to forecast what their properties would In 1945, the last gap in the table ments known today. Nobody knows be. And he was right: the gap was soon was filled. Had science at last discov- how many are yet to be discovered. filled by gallium and germanium. ered all the elements? Curiously, the What is known, though, is that cre- With a few refinements and modi- answer is both yes and no. All the ating new elements is getting harder. fications, the table that Mendeleev elements that exist naturally on Earth Today, you need the most advanced labs created became what we use to this were known. But – and it’s a big but in the world if you are to stand a chance: day: the periodic tablew1, something so – there was nothing to say that new the easy ones have all been found. basic that we never stop to think that elements could not be created artifi- it had to be invented. cially, tagged onto the end of the peri- * * * In the following decades, chemists odic table beyond element number 92, Known by the tongue-twisting raced to fill the remaining gaps. Along uranium. name ununennium, the predicted the way, they also discovered why the So with the development of atomic element that an international team is periodic table works: the rows and research in the 1940s, just as the last focusing on today is likely to be the columns mirror the way electrons are holes in the table were being filled, hardest yet.

Chemistry school and it can be very useful to make science more Physics appealing to students, especially to those more interest- History of science ed in the humanities. This article could be used to demonstrate the links between the sciences and humanities. Ages 14+ Potential comprehension questions include: After a brief summary of the creation and evolution of the periodic table, this article introduces current re- 1. According to Ancient Greeks, how many elements were there? search to discover new elements. It could be used in chemistry and physics lessons, particularly when study- 2. What is the atomic number? ing nuclear chemistry, atomic physics or the history of 3. How many elements does the periodic table cur- science. The article could also be used to discuss the rently comprise? scientific method, the velocity of scientific progress, the 4. Describe the method used by the team to try to dis- difficulties that researchers encounter and the useful- cover new elements. What are the problems associ- ness of basic research. ated with this method?

REVIEW History of science is a topic rarely seen in secondary Mireia Güell Serra, Spain www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 19 Image courtesy of G Otto / GSI

Creating ununennium: team members Professor Christoph Dül- lmann and Dr Alexander Yakushev in front of the experimental setup. With the aid of a particle accelerator, titanium ions are accelerated to close to the speed of light, after which they pass along the silver tube on the left and smash into a target made of berkelium (in the yellow-striped box in the centre). Using three magnets (red boxes on the right), the resulting ununennium ions are separated from all other particles, after which they enter the detector, where their decay can be registered.

To make element 119, scientists plan to fire an intense beam of titanium atoms into berkelium.

The team, co-ordinated by the GSI Helmholtz Centre for Heavy Ion Research (GSI Helmholtzzentrum für Schwerionenforschung), in Germany, and involving about 20 research centres from around the world, plans to create element 119. Their method sounds deceptively simple: fire a beam of titanium atoms (atomic number 22) into some berkelium (97). Add the two together and – eureka! – you get 119. Of course it’s not so easy. First of all, highly radioactive berkelium doesn’t exist in nature either: it first has to be created in a nuclear reactor. Moreover, it’s ludicrously hard to actually smash the elements Image courtesy of NikNaks; image source: Wikimedia Commons together. “It is extremely difficult to create antee a win. It’s slow and inefficient, because you only ever have a single intense titanium beams. To accom- but it’s a numbers game, and you’ll atom at a time and for just a fraction plish this, we have secrets that we get there eventually. of a second. will not share with others,” explains But there’s another problem. All the The team’s solution is to create the Professor Jon Petter Omtvedt, one of heavy elements are radioactive: their ununennium with the aid of a particle the team members. “We shall bom- atoms break down into lighter ones accelerator, then fire it into a detec- bard the plate with a beam of five over time, releasing radiation. And the tor and look for the tell-tale signs of trillion [5 x 1012] titanium atoms per heaviest elements discovered have all ununennium nuclei disintegrating – second. [...] The probability of a direct been incredibly unstable. Ununoctium radiation and the atoms that it breaks hit [between the atoms] is extremely (element 118) decomposes within mil- up into – rather than the ununennium low. When the atoms collide with liseconds of being created; ununen- itself. each other on rare occasions, they are nium may be even shorter-lived. It’s a clever solution, but it leaves usually merely shattered or partly It’s not that they’re dangerous – the one of the team’s ambitions out of destroyed in the collision. However, amounts are so tiny that the dose of reach: they would love to be able less than once a month, we will get a radiation is safe. But it makes it dif- to study how atoms of these exotic complete atom.” ficult to study the element you’ve just elements react with each other. But That’s like winning the lottery jack- created: you can’t drop it in a test-tube that’s probably never going to be pos- pot by buying enough tickets to guar- or heat it in a Bunsen burner flame, sible, at least not using any kind of

20 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Cutting-edge science

Image courtesy of stock photos for free.com Image courtesy of Alchemist-hp; image source: Wikimedia Commons

Zinc Chemistry

technology we can imagine today. Racing to be the first to create the But if your job is to create new world’s heaviest element: elements for a living, beating lottery www.apollon.uio.no/english/ jackpot odds along the way, ‘impossi- articles/2011/element1.html ble’ might sound like a challenge.... The world’s most difficult chemical Acknowledgement experiment: the struggle to discover The editors of Science in School the secret of super-heavy elements: would like to thank Professor Chris- www.apollon.uio.no/english/ toph Düllmann from the GSI Helm- articles/2011/element2.html holtz Centre for Heavy Ion Research The University of Nottingham, UK, for his help with this article. has created a website with videos Web reference relating to each of the elements in w1 – The International Union of Pure the periodic table. For a review of and Applied Chemistry (IUPAC) is the website, see: the official body that decides wheth- Walsh M (2012) Review of Image courtesy of Shape; image source: Wikimedia Commons er an element has been discovered. the Periodic Table of Videos The IUPAC periodic table includes website. Science in School 24. been a journalist and science commu- all elements from 1 to 112, as well as www.scienceinschool.org/2012/ nicator, and currently works as a pub- elements 114 and 116. Elements 113, issue24/videos lic information officer for the NASA 115, 117 and 118 are not officially The website of the UK’s Royal Soci- / ESA Hubble Space Telescope. He is recognised by IUPAC, although ety of Chemistry offers an interac- a co-author of the book An Element of claims have been made in the scien- tive version of the periodic table, Controversy: The History of Chlorine in tific literature about the discovery of with all 118 known elements. Visit: Science, Technology, Medicine and War. these elements. The IUPAC periodic www.rsc.org/periodic-table table can be downloaded from the IUPAC website (www.iupac.org) or If you found this article interest- via the direct link: http://tinyurl. ing, you might like to browse com/iupactable all the chemistry-related articles in Science in School. See www. Resources scienceinschool.org/chemistry Two press releases from the Univer- sity of Oslo, Norway, provide more Oli Usher is a science writer. He information on the hunt for ununen- has a postgraduate degree in the his- To learn how to use nium: tory and philosophy of science, has this code, see page 65. www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 21 Image courtesy of swisscan; image source: Flickr

Magnetic science: developing a new surfactant

With the use of detergents and other surfactants on the rise, the resulting pollution is worrying. One answer: surfactants that can be collected and re-used simply by switching a magnetic field on and off.

By Julian Eastoe, Paul Brown, cloth and leather for dyeing, in car Isabelle Grillo and Tim Harrison washes and for cleaning and sanitis- ing hospitals. Once they have per- t has been estimated that each formed their cleaning task, the resi- person in the EU uses about dues are simply washed away into the 10 kg of detergents annually. sewers and eventually released into ThisI includes not only the bars of the environment. Imagine that instead soap, shampoos, toothpastes, wash- these residues could be recovered. ing powders and household cleaning This article describes some of the lat- agents we are familiar with, but also est research into recyclable detergents, detergent-type compounds found in and how they can be studied using fuels, pharmaceuticals and even foods advanced research methods. and beer. In industry, huge quantities of detergents are used, for example in

commercial laundries, in preparing Image courtesy of Roadsidepictures; image source: Flickr source: image Roadsidepictures; of courtesy Image

Automatic car washes use a lot of detergent.

22 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Cutting-edge science Image courtesy of autowitch; image source: Flickr

Detergent residues are washed into Soaps, detergents and surfactants the sewers and Surfactants are compounds that lower the surface ten- ultimately released into the environ- sion of a liquid, making them suitable for a number of ment, where they applications – such as emulsifiers, foaming agents, wetting can be harmful. agents and dispersants, for example. Surfactants or mix- tures of surfactants that are used in cleaning are known as detergents. The simplest and oldest of all detergents is Image courtesy of Gustavo (lu7frb); image source: Flickr soap, used in Babylon almost 5000 years ago; in fact, soap Chemistry manufacture is one of the oldest chemical industries. Sodium dodecanoate (figure 1) demonstrates the general structure for all surfactants: one part of the molecule is hydrophilic, meaning it will be soluble in water as it has Toothpaste a charged ‘head’, and the rest of the molecule is an oily contains hydrophobic ‘tail’. The ability of a detergent to dissolve detergents. in water is due to a balance of intermolecular forces. The head is a negatively charged carboxylate ion able to form Physics hydrogen bonds with water, whereas the hydrophobic tail cannot hydrogen bond because it is a long alkane chain, with no electronegative elements present. This explains

Image courtesy of The Matrix; image source: Flickr why surfactants aggregate in clusters, known as micelles (figure 2, page 24), which are essential for the action of detergent cleaners. Image courtesy of the University of Bristol

- + Figure 1: Sodium dodecanoate, C11H23COO Na , showing the long hydrophobic hydrocarbon tail and the hydrophilic carboxylate head structure Image courtesy of Roadsidepictures; image source: Flickr Image courtesy of schoeband; image source: Flickr

The earliest detergent: soap Image courtesy of GeorgHH; image source: Wikimedia Commons

The two ends of the detergent also behave differently with non-polar stains such as grease. The hydrophobic tails interact with the grease, while the hydrophilic heads attract water molecules through hydrogen bonding. After a little agitation, the grease leaves the material to which it was attached, forming detergent droplets containing grease; the droplet surfaces consist of the water-soluble hydrophilic heads. The grease is therefore removed from the material www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 23 Hydrophobic tail

Image courtesy of Mariana Ruiz Villarreal; image source: Wikimedia Commons that you really have produced a mag- Liposome Figure 2: A micelle is the basic structure netic surfactant? D needed for detergents to clean greasy stains: C the grease can be incorporated into the oily To begin with, the Bristol research- central core (A) of the micelle. The hydropho- ers took a known surfactant and bic tails (B) interact with the oil and grease replaced its bromine group with an (A), while the hydrophilic heads (C) hydrogen iron-containing group (figure 3). They bond with the aqueous solution (D). then demonstrated that the compound still functioned as a surfactant: it was Micelle capable of lowering the surface tension of liquids, and could cause them C D to foam. Next, the group demonstrated that the iron in the head group had conferred the desired magnetic A activity. To really understand what was D B happening, however, the researchers needed to look more closely at their B compound. For example, although Bilayer sheet its ability to lower surface tension D strongly indicated that it was forming micelles, it was not conclusive proof. To test this, the researchers used a super-sensitive specialist technique B C called small-angle neutron scattering (SANS). D Surfactants can be imaged using small-angle neutron scattering and held in the water by these mi- magnetic surfactants, which respond SANS is an excellent technique for celles (figure 2). to a magnetic field as a result of iron investigating structures about 0.1-100 atoms in their head groups (figures 3 nm in size; perfect, then, for searching Developing magnetic surfactants and 4). These surfactants could have and characterising surfactant micelles A research group at the Univer- both environmental and medical and emulsion droplets, which are sity of Bristol, UK – including two applications (see below). typically 2-10 nm in diameter. SANS of the current authors – is currently How were the magnetic surfactants is also widely used to investigate soft working on a new type of surfactant: developed? And how do you prove matter (e.g. polymers, colloids and

Images courtesy of the University of Bristol Image courtesy of the University of Bristol

Figure 3: Developing a magnetic surfactant from a conventional surfactant.

A) The structure of dodecyltrimethylammonium bromide, a non-magnetic surfactant that the Bristol group took as one of the starting materials

Figure 4: The effects of a magnet on solutions of normal (left, with added dye to show the two layers) and magnetic (right) surfactants. B) The structure of dodecyltrimethylammonium trichlorobromoferrate, one The presence of iron in the magnetic surfactant of the magnetic surfactants that the Bristol group is working on explains the attraction seen on the right.

24 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Cutting-edge science

More about ILL

SANS experiments require intense beams of neutrons, which can only be produced at large facilities. In Europe these are done at laboratories jointly funded and run through inter-governmental collaborations,

such as ISISw2, in the UK, and the Institut Laue-Langevin (ILL)w3, in France. Chemistry ILL is an international research centre operating the most intense steady neutron source in the world. Every year, more than 800 experiments are performed by about 2000 scientists coming from all over the world. Research focuses on science in a variety of fields: condensed matter physics, chemistry, biology, nuclear physics and materials science. The magnetic field lines caused in w4 iron pellets by a magnet. Magnetic ILL is a member of EIROforum , the publisher of Science in School. surfactants are magnetic because To see all ILL-related articles in Science in School, they contain iron atoms. see: www.scienceinschool.org/ill Physics

Image courtesy of oskay; image source: Flickr

Image courtesy of ILL liquid crystals), biological molecules (e.g. DNA and proteins in solution) and hard condensed matter (e.g. clusters in alloys, and flux line lattices in supra-conductors). In a SANS experiment, an intense neutron beam is directed onto the sample of interest (figure 5); this beam can be viewed as a stream of free particles travelling in the same direction and with the same speed. The free neutrons in the beam interact with the bound nuclei of the atoms in the sample, scattering the beam. These Figure 5: Schematic representation of a small-angle neutron scattering experiment. The incident k and scattered k wave vectors are shown, along with the resultant scattered neutrons are recorded by a i s scattering vector q, which is in the plane of the detector. position-sensitive detector. The resulting data – the intensity of the neutrons scattered by different areas of the sample – is used in mathematical models pound, the SANS results provided the investigate – the behaviour of their to determine the shape, size and first conclusive proof that it really was surfactant under different conditions. charge of the scattering objects in the forming micelles. Using SANS, the team was also sample. For a more detailed explana- Furthermore, the scientists were able to test whether in solution, the tion of SANS analysis, download the able to show that the micelles formed iron particles dissociated from the supporting materials from the Science by the new surfactant were small, surfactant, effectively resulting in a in School websitew1. spherical and uncharged. This was mixture of non-magnetic surfactants For their SANS analysis, the Bristol important, because the behaviour of a and dissolved magnetic particles, or group teamed up with scientists at the surfactant, and thus its applications, whether the two elements remain Institut Laue-Langevin (ILL; see box are affected by characteristics of the bound, forming genuinely magnetic above) in Grenoble, France. Although micelles and emulsion droplets that it micelles. The results suggested that other surfactant properties such as forms with different liquids. With this the iron compounds were firmly in- surface tension reduction had already information, the scientists are now tegrated in the micelles. This opened been observed with the new com- better able to predict – and in future up the possibility of creating magnetic www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 25 The Deepwater horizon oil spill in the Gulf of Mexico, as seen from space in 2010. The spill was the largest in the history of the petroleum industry. Detergents were used to try to disperse the oil.

Future prospects Magnetic surfactants are not the only new type of surfactants that are currently being developed in Bristol. The research team are also investigat- Image courtesy of NASA ing surfactants that can be turned on and off by changes to light, pH, emulsions with potential medical ap- netic surfactants were used instead, temperature, pressure and carbon plications (see below). the resulting emulsions could be col- dioxide concentration. The current lected, removing both the oil and the challenge is to learn how to scale up Magnetic surfactants have surfactants from the water. the synthesis of these surfactants to environmental and medical Magnetic surfactants may even make these smart surfactants cheaply applications have medical applications. Targeted and effectively. Magnetic surfactants may sound drug delivery aims to get medica- like a strange idea, but they have tion only to the specific cells where it some very practical applications. For is required, preventing the waste of Julian Eastoe is a professor of example, many surfactants are not valuable pharmaceutical compounds chemistry, specialising in surfactant biodegradable. If magnetic surfactants and minimising side effects. Figure 6 chemistry at the University of Bristol, were used instead, they could be shows how emulsion droplets (dyed UK. Paul Brown is a PhD student, retrieved from waste-water using a blue) formed from the magnetic investigating novel surfactants at the magnetic field and recycled, resulting surfactants can be manipulated with University of Bristol, UK. Isabelle in lower levels of detergents entering a small magnet efficiently enough to Grillo is an instrument scientist at the the environment. overcome typical blood flow in the Institut Laue-Langevin in Grenoble, Moreover, currently when there body. These emulsions could encase France. is an oil spill at sea, surfactants are medication in the same way as emul- Julian Eastoe and Paul Brown came used to break oil slicks into emulsion sions currently used in drug delivery, up with the idea of magnetic sur- droplets so small that they diffuse but the magnetic emulsions could be factants and carried out the laboratory away into the ocean, where the oil directed to the right spot in the body experiments (with the help of Profes- remains a pollution hazard. If mag- with a magnet. sor Annette Schmidt from the Univer- sity of Cologne, Germany). Isabelle Grillo was heavily involved with the neutron scattering and data analysis. Tim Harrison also works at the Uni- versity of Bristol, as the school teacher fellow at the School of Chemistry. This is a position for a secondary-school teacher that was created to bridge the gap between secondary schools and universities, and to use the resources Figure 6: The effect of a magnetic field on a magnetic emulsion: the magnet of the School of Chemistry to promote drags the droplet uphill, against gravity. Once the magnet is removed (picture 5) chemistry regionally, nationally and gravity causes the droplet to flow back down the tube. internationally. Tim is a frequent au-

Image previously published in Brown et al. (2012a). Reproduced by permission of The Royal Society of Chemistry thor for Science in School.

26 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Cutting-edge science

Reference environment, pharmaceuticals and ties with responsive surfactants. health care, through to nanotechnol- Angewandte Chemie 51: 2414-2416. Brown P et al. (2012a) Magnetic emul- ogy, materials engineering and IT. doi: 10.1002/anie.201108010 sions with responsive surfactants. See: www.isis.stfc.ac.uk Soft Matter 8: 7545-7546. doi: For teaching activities on surface 10.1039/C2SM26077H w3 – More information about ILL: tension and surfactants for primary www.ill.eu school, see: Web references w4 – EIROforum is a collaboration Kaiser A, Rau M (2010) LeSa21: w1 – To learn more about SANS between eight of Europe’s largest in- primary-school science activities. analysis, download the supporting ter-governmental scientific research Science in School 16: 45-49. www. Chemistry material from the Science in School organisations, which combine their scienceinschool.org/2010/issue16/ website: www.scienceinschool. resources, facilities and expertise lesa org/2012/issue25/soap#resources to support European science in If you found this article useful, why w2 – ISIS is a world-leading centre reaching its full potential. As part of not browse the other chemistry- its education and outreach activi- for research in the physical and life related articles in Science in School? ties, EIROforum publishes Science sciences that uses a suite of neutron www.scienceinschool.org/ in School. To learn more, see: www. chemistry and muon instruments to under- Physics eiroforum.org stand the properties of materials at the scale of atoms. An international Resources community of more than 2000 sci- For more details of the research, see:

entists uses the facility to research Brown P et al. (2012b) Magnetic To learn how to use subjects from clean energy and the control over liquid surface proper- this code, see page 65. General science Primary

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 27 Movers and shakers: physics

in the oceans North America Contrary to the popular saying, deep waters North Atlantic are often far from still – which is just as well Ocean for marine life. Activities using simple water tanks are a good way to find out about the physics at work beneath the waves.

By Susan Watt Part of the answer is gravity. Grav- university oceanographers in Maine, ity acts on water masses of different USA, noticed a few years ago that density and this, together with wind their marine science students seemed hen we think about and Earth’s rotation, produces forces unaware of the physics involved in climate change, one of and currents within the oceans. Such their subject, focusing instead mainly the biggest concerns is processes not only have a potential on the biology. As a result, they thatW major ocean currents such as the impact on our climate, but are also a decided to put together a teaching Gulf Stream are being sent off course, huge influence on the environment resource to convince students that jeopardising the weather systems that inhabited by marine organisms. oceans are an unusually exciting place depend on them. But what causes As a result, any student of oceanog- to study physics. This article is based such currents to be established in the raphy will need a good understand- on that resource (Karp-Boss et al., first place? ing of these processes. But a group of 2009), which focuses on key concepts in physics that are also fundamental in oceanography, and provides a

Image courtesy of somebody_; image source: Flickr compelling environmental context for Physics ideas within physics. Of course, students learn best when Biology they are actively engaged, so central Ages 12+ to the resource is a series of activi- Physics is often seen as unrelated to everyday life, which makes many ties designed to engage students and students uninterested in the subject. This article uses oceanography to challenge their assumptions. Two ac- provide a context for physical concepts, thus helping to raise students’ tivities that the oceanographers have interest. It could be used in biology or physics lessons, particularly when studying marine topics. The two activities described can either be used by teachers as demon- strations or carried out by students. They can be used before explaining the physics concepts that appear in them (to make students think about them) or after their explanation. Additional exercises about physical oceanography that would be useful for teaching physics to students aged 12-18 are listed at the end of the article. Finally, the text could help students understand that seemingly diverse scientific subjects can be interlinked. For example, to understand how the environment affects marine life, we need concepts from physics (and also chemistry and geology).

REVIEW Mireia Güell Serra, Spain

28 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Image courtesy of Nicola Graf Teaching activities

The Gulf Stream is one of the strongest ocean currents in the world. It originates at the tip of Florida Europe in the US, then follows the eastern coastlines of the USA and Newfoundland, Canada, before crossing the Atlantic Ocean towards the British Isles. The Gulf Stream is driven by winds and differences in water density. Surface water in the north Atlantic is cooled by winds from the Arctic, whereupon it becomes denser and sinks to the ocean floor. This cold water then moves towards the Equator where it is slowly warmed. To replace the cold water North Atlantic moving towards the Equator, warm water moves from the Gulf of Mexico north into the Atlantic. Ocean Africa

Greenland Equator Antarctica Physics Figure 1: In open ocean regions, there are at least Surface Mixed layer three distinct water layers: an upper mixed layer 300 of warm water; the thermocline, in which the Thermocline temperature decreases rapidly with increasing 600 depth; and a deep zone of cold, dense water in which density increases slowly with depth. 900 The three layers are illustrated in this cross-sec- Depth (m) Deep layer tional diagram of the Atlantic Ocean. Note that 1200 the thickness of the layers varies with latitude. At 1500 high latitudes, only the deep-water layer exists. 60° 40° 20° 0° 20° 40° 60° North Latitude South

Image from the DataStreme Ocean project. ©American Meteorological Society. Used with permission.

Image courtesy of Lee Karp-Boss used successfully in their classes are sinking from surface to deep waters described here: one focusing on den- are just two examples. sity, the other on waves. Both could be Whereas the density of water used with secondary-school students ranges from 998 kg/m3 for fresh of all ages (11-19). water at room temperature to nearly The first activity shows how strati- 1250 kg/m3 in salt lakes, ocean waters fication occurs as a result of density have a much smaller density range differences due to temperature or (about 1020–1030 kg/m3). Most of salinity. The second activity looks at the variability in seawater density is internal waves; resonance and natural due to salinity and temperature. As Density layers. The top image shows frequency are also demonstrated. For salt concentration increases, due to the tap water and salt solution before both activities, the apparatus is set up the divider is removed. Afterwards evaporation or ice formation, density prior to class, and the students carry (lower image), the salt solution forms increases. Higher temperatures reduce out the activities for up to 30 minutes a stable layer at the bottom of the density, whereas cooling increases it. per activity (using worksheets). The tank with the tap water above it. Ocean seawater density increases last part of the lesson is used for sum- with depth, but not in a uniform way: marising findings and discussion. instead, water of different densities In oceanography, density is used to forms a series of layers (figure 1). Density and stratification characterise water masses and to This stratification acts as a barrier Density is a fundamental property study ocean circulation. Many ocean for the exchange of nutrients and dis- of matter. It is the mass per unit vol- processes are caused by differences solved gases between the top, sunlit ume of a material – that is, how much in densities: large-scale ocean circula- layer where phytoplankton thrive, mass is packed into a given volume. tion and carbon transport by particles and the deep, nutrient-rich waters.

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 29 1 The upper layer of water cools and sinks. 4 The surface layer cools further and ice starts 2 Warmer (not yet cooled) water rises to to form on the surface. This is stable, as it is replace it. less dense than water below. 3 The process repeats, cooling whole lake to 5 With more cooling, the whole lake freezes. the temperature of maximum density (4°C).

1 2 3 4 5

Density is fundamental to how lakes freeze. As winter approaches in high Image courtesy of Nicola Graf latitudes, lake waters are cooled from the top. When the upper waters become cooler and denser than the waters below, they sink. The warmer, less dense water underneath then rises to replace the sinking water. If low air temperatures persist, Mixing stratified layers requires work: these processes will eventually cool the entire lake to 4 °C – the temperature of maximum density for fresh water. With yet further surface cooling, the density of think how hard you need to shake a the upper waters will decrease, and the lake becomes stably stratified with colder bottle of salad dressing to mix the oil but less dense water at the top. As surface waters cool to 0 °C, they begin to and vinegar. So, without enough ener- freeze. If cooling continues, the frozen layer deepens. getic mixing due to wind or breaking waves, phytoplankton at the ocean’s surface will lack nutrients. Image courtesy of Moroder; image source: Wikimedia Commons the ‘natural modes’ of the basin – in Types of waves a similar way to sound waves in a Although density is not the first musical instrument, where a particu- thing that comes to mind when we lar frequency is produced by a given think of the sea, waves are a differ- length of string or air column. This ent matter. Waves are ubiquitous in phenomenon is called resonance. the ocean, in lakes, and of course on In oceanography, there is an ad-

beaches – and they are feared in their ditional phenomenon known as seiche Image courtesy of Raymond Larose; image source: Flickr destructive form as tsunamis. (pronounced ‘saysh’, from an old Most of these waves are what physi- French word meaning ‘to sway’). This cists call surface waves. But there are is when a standing wave is estab- also internal waves, which occur at lished in a semi-enclosed body of the interface between density layers of water, which moves from side to side water. In the ocean, breaking internal as a mass – rather like tides. For ex- waves mix up the water layers and lift ample, the Adriatic seiche, which has the nutrients they contain. a period of 21.5 hours, is associated The geometry of a water basin Acqua alta (‘high water’ in Italian) with serious floods in Venice, Italy. is the name given to the high water (such as a lake or a bay) determines Other naturally occurring examples levels that occur periodically in the which waves are excited when force Venetian lagoon. The phenomenon of seiches have been observed in Lake is applied and then released (e.g. due occurs in part due to the Adriatic Geneva and in the Baltic Sea. to a passing storm). These waves are seiche. Shown here is Venice’s famous Piazza San Marco, partially sub- merged during an acqua alta in 2004. A frozen lake

30 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Teaching activities

Activity 1: Investigating water density and stratification

Materials 2. Place the tap water in one 8. Place the hot water in one tank compartment of the tank and salt • Rectangular tank with a divider compartment and the ice-cold solution in the other. water in the other. What do you • Bottle containing salt solution 3. Add a few drops of food colouring predict will happen when you (approximately 75 g salt dissolved to the water in each compartment, remove the divider? Explain your in 1 l water) so that each has a different colour. reasoning. • Two beakers containing tap water, 4. What do you predict will happen 9. Remove the tank divider. What at room temperature when you remove the divider happens? Is it as you predicted? • Food colouring (two different between the compartments? 10. After observing the new colours) Explain your reasoning. equilibrium in the tank, place • Ice your fingertips on top of the fluid 5. Remove the tank divider. What Physics surface and slowly move your Procedure happens? Are your observations consistent with the densities you hand towards the bottom of the 1. Calculate the densities of the tap measured? tank. Can you feel a temperature change? water and the salt solution. To do 6. Empty the tank and the beakers. this, students measure the weight Now fill one beaker with hot tap 11. How might the effects of climate of a known volume of water, mak- water and one beaker with ice-cold change, such as warming and ing sure to subtract the mass of the water. melting of sea ice, affect the container from the total mass of vertical structure of ocean water? 7. Add a few drops of food colouring the container plus liquid. The den- Discuss possible scenarios. to each of the beakers (a different sity can then be calculated, since colour in each beaker). density (r) is mass (m) divided by volume (v) (or r = m/v). Image courtesy of Hamed Saber; image source: Flickr

A frozen lake

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 31 Activity 2: Investigating internal waves

Materials the interface between the two Discussion • Rectangular tank with a divider differently coloured fluids. The energy of internal waves is • Stopwatch Measure the speed of this wave generally lower than that of surface by timing how long it takes for waves. This is because the gravita- • Food colouring or other the wave to travel the length of tional restoring force is smaller for appropriate dye the tank. (Make sure you use an internal waves, due to the relatively • Two containers: one with fresh average value by timing several slight difference in density between water and the other with dyed traverses.) Find the speed of the water layers (compared to that salt water (approximately 75g salt wave using the formula: between water and air for surface dissolved in 1 l tap water) Length of tank (m) / time taken waves). This lower energy means that, • Wave paddle (a wide piece of (s) = wave speed (m/s) for a tank (or water basin) of a given plastic about 2 cm high, with a 4. Try producing surface and inter- size, the natural frequency of the width similar to that of the tank) nal waves using the wave pad- internal waves will also be lower than • Optional: a piece of plastic the dle. For surface waves, lower the for surface waves. same width as the tank but about paddle into the water and raise it In additional to surface waves, strat- one-third of its length again, repeating the cycle at a fast ified fluids support internal waves; in two-layer fluids, these waves ride on Procedure frequency (at least once a second). For internal waves, do this more top of the interface between the two 1. Place the tap water in one slowly (about once every 10 sec- fluids. Their periods are significantly compartment of the tank and the onds). longer than those of surface waves coloured salt solution in the other. and their amplitudes can be signifi- 5. Discuss your results. cantly higher. When we perturb the 2. Remove the divider between the 6. Optional: if you have time, you two-layer system, many waves are compartments, and watch what can repeat the experiments using initially excited, but only those that happens. Make a note of any the piece of plastic inserted at an fit (resonate) with the geometry of the waves you see, and describe their angle to the bottom of the tank, basin remain. Inserting the piece of movements. to give the effect of a shallow sea plastic at one end of the tank, simulat- 3. Identify the internal wave – this bed. Place the plastic in position as ing an increasingly shallow seabed, travels back and forth along shown below. can cause internal waves to break, similar to surface waves breaking on a beach, but occurring below the surface.

Image courtesy of Lee Karp-Boss

An internal wave at the interface between the denser

(blue) salt water and less dense (clear) water. A wave Image courtesy of stock photos for free.com paddle is shown on the right of the tank, and a piece of plastic to simulate shallow topography on the left.

32 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Physics Image courtesy of Isolino; image source: Flickr 33 I

- ? Issue 25 : Winter 2012 Winter Issue 25 : I

Science in School To learn how to use learn how To Teaching activities Teaching this code, see page 65. Susan Watt is a freelance science is a freelance Susan Watt shorter link: http://tinyurl.com/ shorter link: cf4so47#). on ocean cur tion and resources . See: http://oceanmotion.org/ rents index.htm on web- available oceanography are for Ocean site of COSEE (Centers Excellence). Sciences Education See: www.cosee.net/resources/ educators to oceanography: introductions Denny MW (1993) Air and Water: Me- The Biology and Physics of Life’s dia. Princeton, NJ, USA: Princeton University Press Denny M (2007) How the Ocean to Oceanogra- An Introduction Works: phy. Princeton, NJ, USA: Princeton University Press the other teaching not browse activities in www.scienceinschool.org/teaching writer and editor with a special She in science education. interest studied natural sciences at the Uni- versity of Cambridge, UK, followed by master’s in philosophy degrees She has of science and psychology. worked as a curator at the Science Museum (London) and produced international exhibitions for the a British Council, and is currently school governor and event organiser Association. for the British Science NASA offers a website with informa- a website offers NASA educational resources in Additional educational resources accessible These two books are If you found this article useful, why Science in School Science in School , -

Image courtesy of Biopics; image source: - Wikimedia Commons

Image courtesy of Uwe kils; image source: of Uwe kils; image source: Image courtesy Commons Wikimedia on ocean layering and mixing, see the article Mix it up, mix it down: In triguing implications of ocean layering available online at: www.tos.org/ oceanography/archive/22-1_franks. pdf and images of density profiles offers videos thermohaline circulation, on ocean convection, a collection of hands-on activities, and links to concepts. See: http://cosee. related umaine.edu/climb videos dem are there In particular, onstrating activity 1: water density and stratification (http://cosee. umaine.edu/files/coseeos/ video_tsoi04.htm or use the shorter link: http://tinyurl.com/crjzwoq) and activity 2: internal waves (http://cosee.umaine.edu/files/ or use the coseeos/video_tsoi11.htm For more information and activities information and activities For more The website of COSEE Ocean Systems This article is based on the resource This article is based on the resource sciencekit.com, where a set of six sciencekit.com, where could You tanks costs 130 USD. also try building your own, using a a small fish tank and constructing divider with a good seal. physical concepts in oceanography: . Ocean- an inquiry based approach ography 22(3): supplement. doi: 10.5670/oceanog.2009. supplement.01 Image courtesy of Lycaon; image source: developed through the organisation the organisation developed through COSEE (Center for Ocean Sciences Education Excellence) by oceanographers Lee Karp-Boss, Emmanuel Boss, - James Loftin and Jen Herman Weller, Albright (Karp-Boss et al., 2009). nifer Resources The tanks can be obtained from Teaching Karp-Boss L, et al. (2009) Teaching Reference Acknowledgement Image courtesy of Biopics; image source: Wikimedia Commons Wikimedia Image courtesy of Biopics; image source: Planetonic organisms are incapable against a current. of swimming Wikimedia Commons www.scienceinschool.org 34 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science topics Biology Chemistry Physics General science Primary

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 35 Image courtesy of chris2766 / iStockphoto.com

Exploring scientific research articles in the classroom Learn how to use research articles in your science lessons. Research articles are By Miriam Ossevoort, Marcel that their argument is correct. It is generally written Koeneman and Martin Goedhart now easier than ever to read the origi- in the third nal research behind science stories in person cientists use research articles the media, as more and more arti- 3 to communicate their research cles are being made freely available findings and scientific claims. through open-access publishing. SThese articles are not just factual building on existing knowledge) Reading research articles is an op- Reading research articles is not an

Image courtesy of JakobVoss; image source: Wikimedia Commons reports of experimental work; the authors also try to convince the reader portunity for secondary-school stu- easy task for students, but they can dents to learn about: find it inspiring. Here we describe a • The language of scientific classroom activity that we have been communication (structure, using to teach students aged 15-16 vocabulary and conventions such as years and older about the textual Open-access logo, writing in the third person) structure (part 1) and the argumenta- designed by the Public • Library of Science. The way scientists use their tive structure (part 2) of a research Open-access publishing evidence to form an argument and article. This classroom activity takes makes it easier for you justify their claims about three hours. It could be less if, and your students to ac- • How science works (designing after part 1, the students read the arti- cess scientific research research to test hypotheses; fair cle as homework. articles. testing; presenting results; drawing Most research articles are written conclusions; raising new questions; in English, the language of science. If

36 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Potassium permanganate is an antidote for snake venom Molecular basis of transdifferentiation of pancreas to liver Teaching activities Metallic phase with long-range orientational order and no translational symmetry Rules for biologically inspired adaptive network design

could be topics covered in media All science subjects such as newspapers, popular science Ages 15+ magazines like New Scientist or Science Using the suggested activity for discussing or exploring a few well- News, or their corresponding websites. chosen research papers with students, teachers can not only deepen These websites generally allow you their students’ knowledge of the scientific research in question, but to enter search terms and filter by also help them to relate more closely to the professional activities of topic, date and other criteria; some a scientist. of the articles include suggestions for In addition to the questions posed in the article, the teacher could further reading, such as the original also ask the students to discuss peer review. For example, what is peer research articles. You will then need review? Why is it done? By how many reviewers? Why is it important to judge whether the research article (or desirable) that the review process is blind? What is double-blind itself meets the selection criteria listed peer review? The students could also consider the acknowledgements above. section and discuss how science is financed. Research articles on (animal) behaviour or testing medicines often have Some interesting follow-up strategies would be to ask students to de- easy-to-understand experimental pro- sign their own research project and to write a small research paper. If

this were done in two different classes, the students could then review Image courtesy of billaday; image source: Flickr the research papers of the other class, who have investigated the same or a similar topic. Which science lessons and which age groups to target with the activity would depend on the research paper chosen by the teacher. However, the strategy would be most useful for upper-secondary-level students (ages 15-18). The fact that most research papers are in English should General science not be seen as an obstacle, but as an opportunity to implement interdisciplinary projects with language teachers. Betina da Silva Lopes, Portugal REVIEW

Topics covered in the media are a good you teach in a school where English When selecting the topic, you might place to search for Primary is not the language of instruction, you like to focus on something covered research papers might find it helpful to involve the in the school curriculum. Once you English teacher in the activity. have chosen a topic, you may want to start by searching for research articles Getting started published in open-access journals. To begin with, you need to choose a For example, the Directory of Open w1 good research article to use. The fol- Access Journals (DOAJ), a directory lowing criteria are key: of scientific and scholarly journals 1. Limited length (three pages maxi- published in many languages, is one mum) potential starting point. We would w2 2. Appealing, age-appropriate con- also recommend Biomed Central , a tent publisher of 220 open-access, online, 3. Structure including the following peer-reviewed journals in biology sections: abstract, introduction, and medicine. The Public Library w3 materials and methods, results, of Science (PLOS) publishes seven discussion and / or conclusion open-access, peer-reviewed journals 4. Easy-to-understand experimental in biology and medicine. When using procedure these collections, you could search for 5. Simple relationship between the articles on a specific topic or browse data and conclusion the recent research, featured discus- Image courtesy of Valerie Everett; image source: Flickr 6. Obvious practical or social signifi- sions and / or most viewed sections. cance. Another source of inspiration

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 37 We chose an article about Image courtesy of Image AfrikaForce; image source: Flickr contagious yawning in chimpanzees to teach students about research articles.

or her to answer some basic questions. By skimming the article to find the answers, your students will quickly become familiar with the structure of the research article and its content. Questions might include: • Who is the first author of this article? The first author is normally the person who had the idea behind the research or did most of the work. • Who are the other authors? • Where was the research done? • Which sections does the article contain and what is in each section? cedures. One good example is Com- main body of the article starts after • When was this paper published? puter animations stimulate contagious the abstract. • Who funded the research? yawning in chimpanzees (Campbell et In the main body of the article, the al., 2009), which was covered in sev- first section is the introduction. Here 2) The argumentative structure of eral newspapers. We chose this article the authors explain the context of the a research article for its length, its appealing content study, i.e. what other researchers have Remember, scientists write research (looking at pictures of yawning chim- discovered, why this study is impor- articles to try and convince their peers panzees makes you yawn yourself), tant (the gap in knowledge) and what to accept their scientific claims. This the straightforward experimental pro- they are going to do. The second sec- line of reasoning is called the argu- cedure and clear scientific claim. More tion presents the material and methods mentative structure and consists of: the details of how we used the article can in enough detail for other scientists to motive (why the study was done), the be downloaded from the Science in repeat the experiments. In the third objective (what was investigated), the School websitew4. section, the results of the study are main conclusion (the outcome of the summarised in text and presented study), supports (statements, including 1) The textual structure of the as graphs, diagrams and tables. The article fourth section is a discussion of the Let’s begin by looking at the text results. Most importantly, it states and the structure of a research article. the main conclusion (claim), how the It starts with a title, which summarises evidence supports this conclusion and the study and / or its outcome. This the implications for further research is followed by a list of the authors and or for society. After this, you may also their affiliations (i.e. who they work find the acknowledgements where the

for). Usually, the first author is the authors thank those who contributed Image courtesy of JJay; image source: Flickr main researcher and the last author is to the research and identify who the head of the department. Then, the funded the study. The references sec- In a research article, dates of submission and publication are tion lists all the source materials cited the person who given; this shows how long the peer in the article. had the idea or did review and revision process has taken. To study the textual structure of a most of the work is Next, we find the abstract, which sum- research article in class, give each stu- normally the first marises the content of the article. The dent a copy of the article, and ask him author

38 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Teaching activities

Image courtesy of Miriam Ossevoort data from their own research), references (to previous research and refuted Introduction Materials & methods Results Conclusion / Discussion counter-arguments) and one or more implications (which might be a new theory, a new research question, or Objective Main conclusion the impact on society or the research community). Each of these elements is Supports usually found in a specific section of the research article (figure 1). Motive Implication The next step in the teaching activity is to look at the argumentative Supports structure in more detail. Students could read the whole article in detail, Figure 1: The working individually or in small argumentative groups to answer guided questions. structure of a research article and Next, the answers could be discussed the location of the References to enhance the students’ understand- different elements in Campbell MW et al. (2009) Computer ing. the text. animations stimulate contagious First, let your students read the in- yawning in chimpanzees. Proceed- troduction, then ask them to answer ings of Royal Society B. 276: 4255– the following questions: 4259. doi: 10.1098/rspb.2009.1087 • Why was this study done (motive)? • What was investigated (objective)? whether they agree with the authors’ The article is freely available via the Next is the materials and methods scientific claim (main conclusion) journal website (http://rspb. royalsocietypublishing.org) section. In our experience, students and to review the article as a whole General science often find this section hard to un- by playing the role of a reviewer. Veneu-Lumb F, Costa M (2010) Us- derstand due to its highly technical You could use a role play about peer ing news in the science classroom. vocabulary. Therefore, we suggest that revieww5, developed by Sense about Science in School. 15: 30-33. www. you simply explain how the study Science. scienceinschool.org/2010/issue15/ was performed. There are plenty of media stories news Then, the students can read the about contagious yawning, so this results and discussion sections and topic would also be ideal for working Web references answer the questions below either as with news articles. For more details of w1 – The Directory of Open Access homework or in class. Ask them to: using news articles in science lessons, Journals (DOAJ) is a directory of • Identify the main conclusion see Veneu-Lumb and Costa (2010). scientific and scholarly journals (outcome of the study), supports for As a follow-up activity, you could published in many languages. See: this main conclusion (data from ask your students to conduct their www.doaj.org this study or previous research) own version of the experiment de- w2 – Biomed Central is the publisher and the implication (e.g. need for scribed in the research paper. For of 220 open-access, online, peer- further study or impact on society). example if you used the article we reviewed journals in biology and If your students find it difficult to chose, your students could play a medicine. See: www.biomedcentral. identify these elements, let them dis- yawning video from Youtube (search com cuss their answers in groups before for ‘contagious yawning’) to another sharing them with the class. A good class of students (who did not know w3 – The Public Library of Science visual way of doing this is to create what was being tested) and watch (PLOS) publishes seven open- a poster with a structure similar to how often they yawn. As a control, access, peer-reviewed journals in figure 1. The students can then review they could watch a non-yawning biology and medicine. See: their posters in a classroom discus- video of similar length. www.plos.org sion. At the end of this classroom activity, Observations on the natural history of the cuckoo you may want to write out the com- Ready steady slow: action preparation slows the subjective passage of time plete argumentative structure of the research article on the board. Finally, On the electrodynamics of moving bodies encourage your students to discuss Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 39 Potassium permanganate is an antidote for snake venom

Vampire squid: detritivores in the oxygen minimum zone Camouflage and display for soft machines; Circulation and angular momentum in the a phase of superfluid helium-3.

The front cover

Public domain image; image source: Wikimedia Commons of the first volume of Philosophical Trans- actions, the world’s first peer-reviewed scientific journal, published in 1665 Image courtesy of Nature A page from Watson and Crick’s famous 1953 Nature paper, in which they reveal the structure of DNA

w4 – Download an in-depth analy- cal journal archive freely available sis of the structure of Camp- online. See http://royalsociety.org Miriam Ossevoort is an assistant bell et al. (2009) from the Sci- or use the direct link http://tinyurl. professor in science education and ence in School website. www. com/royalsocarchive communication at the University of scienceinschool.org/2012/issue25/ To learn more about authorship of research#resources Groningen, the Netherlands, and con- papers, see: ducts educational research on reading w5 – In a classroom role play, students Dance A (2012) Authorship: who’s science. re-enact the peer-review process, as- on first. Nature 489: 591-593. Marcel Koeneman is a teacher in sessing the quality of a mock study doi:10.1038/nj7417-591a biology and chemistry at an interna- on the effect of chocolate on blood tional secondary school in the Neth- pressure. The role-play materials The article is freely available via the erlands. He is also working towards a and some supporting information Nature website (www.nature.com) PhD on using research articles in the can be downloaded from the or via the direct link: http://tinyurl. classroom. Sense about Science website: com/8h4c4lj Martin Goedhart is a full professor www.senseaboutscience.net/ Venkatraman V (2010) Conventions in mathematics and science education ?page_id=52 of scientific authorship. Science at the University of Groningen, the Resources Career Magazine: 16 April 2010. doi: Netherlands. 10.1126/science.caredit.a1000039 Many Science in School articles link to research papers published in the The article is freely available prestigious scientific journal, Nature. via the Science Career Magazine These papers can be downloaded website (http://sciencecareers. free of charge from the Science in sciencemag.org/career_magazine) School website. Explore our archive or via the direct link: http://tinyurl. for articles that link to Nature pa- com/2uu6hrg pers. www.scienceinschool.org If you found this article useful, you In 2011, the Royal Society, the oldest may like to browse the other teach- scientific academy in continuous ing activities in Science in School. See: To learn how to use this code, see page 65. existence, made its entire histori- www.scienceinschool.org/teaching

40 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science education projects Image courtesy of NASA Galileo and the moons of Jupiter: exploring the

night sky of 1610 Physics Mathematics ICT Simple harmonic motion Uniform circular motion Arcsine function Physics History of astronomy Ages 17+

Jupiter and the Galilean This article suggests a new moons were photographed in enquiry-based way of 1979 by spacecraft Voyager 1 teaching simple harmonic and assembled into this col- motion: students use their lage. They are in their relative knowledge of mathematics, positions but not to scale. physics and information and communication technology to characterise the motion of Jupiter’s moons. They collect data from a Carla Isabel Ribeiro explains how software programme, process it and then plot graphs, mathematics can be used to study particularly of sine and arcsine functions, to calculate Jupiter’s moons – and how students the moons’ orbital periods. can do the same. The interdisciplinary nature of the article serves to make science more enjoyable. In addition, the activity develops soft skills such as the n a January night in 1610, “… I should disclose and Galileo Galilei looked at Ju- presentation of results and piter through his telescope publish to the world the communication. By join- and saw what he thought were three occasion of discovering and ing an international project, O the students would have the stars near the planet. He continued his observations for about two months, observing four PLANETS, opportunity to share their and over this time realised that there never seen from the very results not only with other members of their class but were actually four ‘stars’, which beginning of the world up changed their position around Jupiter. with students from different Galileo concluded that the ‘stars’ were to our own times….” countries.

Corina Toma, Computer in fact planets orbiting Jupiter – the Galileo Galilei in Sidereus Medicean planets, as he named them Science High School at the time, but which are now known Nuncius (Starry Messenger; “Tiberiu Popoviciu” Cluj as the Galilean moons in honour of 1610) Napoca, Romania REVIEW their discoverer (figure 1, page 42).

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 41 Figure 1: Jupiter and the Galilean moons Io, Europa, Ganymede, and Callisto (Jupiter is not on the same scale as the satellites.) Public domain image; image source: Wikimedia Commons Image courtesy of NASA Planetary Photojournal

This discovery of Galileo’s forms right when he claimed that the ‘stars’ the basis of a project that I devised near Jupiter were in fact the planet’s for my 12th-grade physics students satellites. To do this, students col- (17–18 years old) when teaching the lect data about the movement of the topic of simple harmonic motion. The moons using a computer simulation, project builds on a similar activity I and then show that this movement developed earlier, about the motion of has the characteristics of simple har- the Galilean moon Io (Ribeiro, 2012). monic motion, with Jupiter as the cen- Portrait of Galileo Galilei The current project is enquiry-based, tre. At the end of the project, students (Justus Sutermans, 1636) and aims to engage students with a produce a report (a document or pres- rich variety of scientific processes – entation) to describe their findings from exploring historical contexts to and the whole process – and, ideally, to approach it. I spent four months obtaining and analysing experimental share this with students from other working on the project with my stu- results and communicating their con- countries so they can learn to commu- dents, but if you do not have time clusions to others. nicate scientific work internationally. to run the whole project with your The aim of the project is for your The duration of the project will vary students, you could select individual students to prove that Galileo was depending on how the teacher decides activities from it.

Image courtesy of Nicola Graf

Displacement

Period A A

Amplitude Time B B

C C

Figure 2: Plotting the motion of an object attached to a spring against time produces a sine wave.

42 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science education projects

Public domain image; image source: Wikimedia Commons

Figure 4: The 16th century geocentric model of the cosmos, depicted in Bartolomeu Velho’s Cosmographia (1568) Physics

Image courtesy of Carla Isabel Ribeiro Simple harmonic motion and A ment appears to be SHM, due to the uniform circular motion projection of their UCM around the planet onto our direction of vision Simple harmonic motion (SHM) is (figure 3). (The orbits are slightly ec- the term used to describe regular peri- centric, but only to a small degree, so Jupiter Jupiter’s odic motions such as the swinging of the moons can be considered to have a moon a pendulum or the oscillations of an circular orbit and to move at constant object attached to a spring. Plotting a speed.) graph of these motions (distance from the central point against time) pro- Cosmology in Galileo’s time duces the characteristic form of a sine Galileo’s observations of Jupiter’s wave (figure 2). moons were made during a time of SHM can be interpreted as a projec- scientific transition, from the geocen- tion onto one axis of an object that is tric (Earth-centred; figure 4) model of B moving with a uniform circular mo- Aristotle and the Catholic Church to tion (UCM). For example, imagine an the heliocentric (Sun-centred) model. object moving in a circle in a horizon- Galileo, of course, was to take up Time tal plane. If we view this from the side the heliocentric model explicitly some at ‘eye level’ (equivalent to projection years later, in a direct challenge to onto the x axis), we see a to-and-fro Catholic doctrine. However, his tel- motion exactly the same as that of an escopic observations, published in oscillating object attached to a spring. his book Sidereus Nuncius (Starry Mes- Figure 3: The movement of one of the Only when viewing the motion from senger) in 1610, were already causing Galilean moons around Jupiter: A) as seen from above the orbit plane and B) above would we see the movement as friction by contradicting the teachings as seen from Earth (viewed parallel to circular. of Aristotle. In Aristotle’s model, eve- the orbit plane). The black dots represent This relationship between SHM and rything in the cosmos orbits Earth – so the Galilean moon’s positions at equal UCM can be applied to the Galilean the idea of moons orbiting the planet intervals of time. moons as seen from Earth: their move- Jupiter was at odds with this.

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 43 Images courtesy of Stellarium The project step by step from Starry Messengerw1, in which Step 1: 17th century cosmology Galileo describes his observations and conclusions. Ask your students to research the cosmological ideas that were current Step 2: choose the planetarium A in early 17th century Europe. What software effect might they have had on Galileo, You will need to download the free- his investigations and conclusions? ware planetarium programme Stel- Students should also read excerpts lariumw2 or a similar simulation. Then

Images courtesy of Stellarium divide your students into four groups, and assign each group to one of the four Galilean moons (Io, Callisto, Ganymede or Europa).

Step 3: tracking Jupiter’s moons B A Ask your students to use Stellarium to investigate the position of their moon over time: in a table, each group should record the displacement (x) – the distance of their moon from the centre of Jupiter – at a succession of times (t). They will also need to find the maximum displacement (A) of the moon from the planet’s centre. Measurements should be taken at B intervals that differ between the four A moons, depending on their distance to the planet and, therefore, their orbital period. The students should use trial and error to find the most appropriate interval for their moon. Their aim is to obtain at least 10 measurements, one Figure 5: Simulation with the freeware of which should be A. programme Stellarium of Jupiter and its For example, Io is the moon that is moons Europa (A) and Io (B). closest to Jupiter, which means it orbits most quickly. If the students take their measurements at 1 h intervals, Step 4: testing Galileo’s the data will not be sufficient; 15 min conclusion intervals would be more appropriate. The fourth and most complicated For one of the more distant Galilean step is for students to show that Gali- moons, 15 min intervals would result leo was right when he concluded that in more data than is necessary, so a the SHM he observed is produced by longer interval should be used. a moon’s UCM around its planet. To find the centre of the planet on To find the orbital period T of their Stellarium, your students can use the moon, the students will need the red marks around Jupiter (figure 5) to mathematical equation for SHM: draw two lines that cross at its centre. x = A x sin(w t +j) (1) To find the distance from that point to where w is the angular frequency Images of Jupiter and the Galilean moons the moon being studied, they can ei- and j is a constant (the phase con- on 7, 8, 10 and 11 January 1610 as ther use an image programme or print stant), together with the equation link- simulated by the freeware programme off the screenshots and measure the w T Stellarium. ing and : distances with a ruler. w = 2p / T

44 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science education projects

Image courtesy of Carla Isabel Ribeiro Figure 6: A graph of arcsin Graph of arcsin(x / A) = (2p / T)t for the moon Europa (x / A) = (2p / T)t for the 2 moon Europa, using observations made with the software Stellarium. The orbital period, T, of the moon can be calculated from the gradient, 2p / T, and the phase constant of 1 the moon, j, is the intercept on the y axis. x arcsin( / A ) (radians)

0 4 8 12 16 20

t (hours) Physics

where x is the displacement, A the which describes SHM – then it is rea- for the moon Europa. amplitude of the motion or maximum sonable to conclude that it is orbiting The graph above has a gradient of displacement, t is the time and j is a the planet as a moon. 0.0741. constant (the phase constant). Because equation (2) is linear, we Since the gradient is equal to 2p / T, Equation (1) can be transformed can see that if your students use their it follows that: into the linear equation (2), thus: data from step 3 to plot a graph of 2p / T = 0.0741 x = A x sin(w t +j) (1) arcsin(x / A) against t, the gradient ⇒ T =2p / 0.0741 ⇒ x / A = sin(w t +j) will be 2p / T, from which they can = 84.8 h ⇒ arcsin(x / A) = w t +j easily calculate the orbital period T. The more mathematically able stu- Since w = 2p / T The phase constant of the moon, j, dents could then carry out a regres- ⇒ arcsin(x / A) = (2p / T)t +j (2) is the intercept on the y axis. Figure sion analysis of the data to test the If your students observe an object 6 shows an example of a graph that ‘goodness of fit’ to equation (2). The behaving according to equation (2) – your students could plot using data value obtained in the case of Europa

Image courtesy of the Lunar and Planetary Institute Image courtesy of NASA Planetary Photojournal

An impact scar, 140 km wide, on Europa. It formed as the An active volcanic eruption at Tvashtar Catena, a chain of giant surface fractured minutes after a mountain-sized asteroid or volcanic calderas on Io, in November 1999. This image was comet slammed into the satellite. captured by NASA’s Galileo spacecraft. www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 45 Public domain image; image source: Wikimedia Commons

Galileo Galilei shows the Doge of Venice how to use his telescope (HJ Detouche, 1754)

Public domain image; image source: Wikimedia Commons

A replica of the earliest surviving telescope attributed to Galileo Galilei, on display at the Griffith Observatory, Los Angeles, CA, USA

(R2 = 0.998) shows that the data com- In this case, the error may have its showing their results. In science, it ply closely with the equation, and origin in the measurement of A, since is important to communicate, so you thus confirms that this object behaves the moon’s positions were simulated could get your students to make their like a moon in orbit. 1 h apart, and the maximum displace- presentations to students in another The accepted value for Europa is ment could have been reached be- class, or perhaps as part of a school about 3.55 days (85.2 h), which is quite tween two measurements. You could fair or open day. They should think similar to the value calculated above. ask your students to suggest ways to about how best to communicate their The difference between the two val- minimise this error. work. How can they make it simple ues can be a good starting point for a for others to understand? What im- discussion about the accuracy of ex- Step 5: presenting the results ages could they use to help explain perimental results. What might have The last step is for each group of what they did? gone wrong? Were any errors random students to present their work, de- More ambitiously, you could even or systematic? scribing the whole investigation and set up a collaboration with a school

46 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Physics - 47

Image courtesy of NASA / JPL / NASA of courtesy Image Issue 25 : Winter 2012 Winter Issue 25 : I To learn how to use learn how To this code, see page 65. you may like to browse the other you may like to browse articles in Science astronomy-related in School. See: www.scienceinschool. org/astronomy teaches chemis Carla Isabel Ribeiro Science in School If you found this article inspiring, this article inspiring, If you found try and physics at a public Portuguese try and physics at a interested school, and is particularly For the past 12 years, in astronomy. she has taught students ranging in age 13 to 18. from Science educationScience projects -

Europa photographed by by Europa photographed website offers up-to-date informa- website offers its moons, tion about Jupiter and See: including space missions. tem. Physics Education 44: 241. doi: 10.1088/0031-9120/44/3/002 The article can be downloaded the website of from of charge free France, the University of Picardie, (www.u-picardie.fr/~dellis/ Documents/PhysicsEducation/ Not_Experimental) or via the direct link: http://tinyurl.com/blfc4k6 Astronomy), tory Experiences in College, hosted by Gettysburg laboratory exercises USA, offers that illustrate modern astronomical consists of techniques. Each exercise a dedicated computer programme, a student manual, and a techni- Several cal guide for the teacher. involve Jupiter’sof the exercises moons. See: www3.gettysburg. edu/~marschal/clea/ CLEAhome.html http://solarsystem.nasa.gov/ planets the Galilean exploring project equipped moons, using a telescope device (CCD) with a charge-coupled camera, see: (2009) JAM de Moraes IG, Pereira Using simple harmonic motion to follow the Galilean moons – testing Kepler’s law on a small sys third encounter on 9 July 1996 encounter on 9 July Voyager 2 during its close 2 during its close Voyager NASA’s Solar System Exploration System Exploration Solar NASA’s (Contemporary Labora- CLEA Project For an article describing a similar For an article describing

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Physics Education ), Galileo’s famous . On a smaller scale, I would . On a smaller scale, w3 original edition is also available explanation of simple harmonic mo tion, with video and animation. See: www.animations.physics.unsw.edu. au Sidereus Nuncius translation of Sidereus online. See: www.rarebookroom.org/Control/ galsid can simulation used in the project, See: of charge. be downloaded free www.stellarium.org school collaboration in Europe the use of information through and communication technologies in 23 languages, Available (ICT). it has nearly 50 000 members and projects than 4000 registered more schools across between two or more See: www.etwinning.net Europe. (Starry Messenger early work describing discoveries made with the telescope. Pages 17 and 18 contain his observations of the moons of Jupiter for the dates See: in this project. featured http://homepages.wmich. edu/~mcgrew/Siderius.pdf harmonic motion. 47: 268-270. doi: 10.1088/ 0031-9120/47/3/F04 Resources a clear The Physclips website offers w2 – Stellarium, the planetarium website promotes w3 – The eTwinning Web references Web English w1 – Download a recent The Reference its simple CI (2012) Io and Ribeiro in another country. Scientists some country. in another times have to communicate in foreign in foreign times have to communicate but not always, languages – often, I am project, English. Based on this international col hoping to set up an the eTwinning laboration through network also be happy to hear from other from also be happy to hear like to work to- schools that would gether on the project. www.scienceinschool.org Science in the open: bringing the Stone Age to life for primary-school pupils

Taking pupils out of the classroom opens up a whole range of activities for teaching young children about the natural world.

Image courtesy of Ramessos; image source: Wikimedia Commons By Petra Breuer-Küppers Replica of one of the Stone Age paintings in he Stone Age might not have the Altamira cave in been a fun time to live in for Spain. The cave’s dis- our ancestors, but finding covery in 1880 sparked a debate about whether out about it can be an enjoyable and T prehistoric humans had educational experience for younger the intellect to produce children. any kind of artistic ex- For the past decade, my colleagues pression. and I have run an educational initia- tive called ‘a week on the meadow’ Image courtesy of Traitor; image source: Wikimedia Commons Image courtesy of garethwiscombe; image source: Wikimedia Commons in our small school, which caters for

pupils aged 6-18 who have special range of topics centred on science, and A Stone Age educational needs. It started life as a one we think can be easily adapted for arrowhead break from routine, a chance to give primary-age children of all abilities. the younger children a breather from Every year, for a week in spring or the daily timetable of classroom-based summer, two classes of mixed-aged learning. But it has evolved into an pupils (ages 6-11), 20 to 30 children in educational tool for teaching a wide all, swap the classroom for a nearby

Stonehenge is a famous Stone Age monument in Wiltshire, UK.

48 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science education projects

Drawing of a typical Stone Age Image courtesy of Dmitry Bogdanov; image source: Wikimedia Commons hand axe

Image courtesy of José-Manuel Benito; image source: Wikimedia Commons Woolly mammoths were hunted in the Stone Age.

5 cm

meadow to learn in the open air. Ini- us access to his fields, and a local Although we are teaching children tially, my colleague and I ran the pro- scout group who provide us with a with special needs (such as learning ject alone; in the past few years, we yurt in case it rains. With these simple disabilities, concentration problems have had the help of a trainee teacher facilities, we spend our days learning and movement disorders), the beauty and a university student. We also about nature, focusing on a different of the week on the meadow is that have the support of a local farmer, theme each year. In 2010, we investi- it can incorporate a whole range of who lends us the meadow and gives gated life in the Stone Age. activities pitched at different interests and ability levels. A meadow with nearby trees and a stream is ideal, because it can be used Physics to teach a range of topics including General science Environmental education plants, insects, nutrition and even Technology building simple structures. However, Ages 10-15* the concept is flexible enough to be Setting up a Stone Age camp for primary-school children is an excel- adapted to a range of locations and lent example of interdisciplinary teaching and learning. It combines subjects – in previous years, we have physics, environmental education, technology and as many other dis- used the themes of pirates, knights ciplines as the teacher wishes to include. and ladies, the Middle Ages, horses, farm animals, ships, flight and the Primary The proposed activities are novel and offer an alternative way of teach- Olympic games. And if you don’t ing many scientific and technological issues such as building a tent, have access to a meadow, you could collecting, identifying and naming herbs, and basic mechanics (shoot- perhaps use a local park. ing with an arrow). I am not aware of any school in my country (for The project begins a week before either special or mainstream education) that offers such opportunities we head to the meadow, with a box of to its students. books about our chosen theme: in this

It is probably not easy to organise such an activity but neither would Image courtesy of Petra Breuer-Küppers it be impossible. And although the first time might be difficult, the following years should be easier. With proper preparation by the teach- We used a yurt as a shelter from ers and the appropriate support from the school authorities and the rain and to store our materials. parents, the pupils will gain much more from the project than they would by staying in the classroom setting. In addition, getting help from people or groups (e.g. farmers or scout organisations) outside school should also offer many educational and social benefits to the pupils. Instead of taking place on a meadow, the activities can undoubtedly also be transferred to a nearby park or riverbank, which are easier to find in a city. Christiana Nicolaou, Cyprus *Note that the author performs the activity with students aged 6-11. REVIEW

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 49 Image courtesy of Petra Breuer-Küppers

The children dug a latrine and then built a screen around it. Gathering materials and building a screen turned into an interesting activity in its own right. The children had to think about design requirements – such as withstanding moderate wind and rain, and hiding the user from sight. Such activities are an opportunity to learn about basic science and technology through trial and error. Our pupils first tried building a tent-like structure, but that proved too small to get into. A second, more successful attempt taught them that using long, thick sticks, they could build a bigger and more solid structure, but that for privacy, the gaps needed to be filled with smaller things like grass, moss and leaves.

Image courtesy of Project Rastko; image source: Wikimedia Commons case, the Stone Age. As a class, we talk washing paintbrushes, we used water about different aspects of our chosen from the stream. It is certainly useful topic: for example, about the land- to have a shelter (we used a yurt) to scape, the wildlife that roamed over store equipment overnight, or for the it and how humans lived at the time pupils to shelter in during the day if it – hunting animals, gathering plants, rains, but otherwise the infrastructure

living arrangements, family life, tools requirements are minimal. Indeed, Image courtesy of josem.rus; image source: Flickr and so on. Keen children can do some over the next few days. Conditions the basic conditions can actually be extra reading in their free time. are a lot more basic than the kids are turned into a learning experience. The real fun starts when we arrive used to. For the first few years that And of course, it makes the pupils ap- at the meadow on the first day. On we ran the project, we didn’t even preciate their return to the 21st century arrival, the children can freely explore have toilets; instead, the children when they go home each evening. the area they will be getting to know dug a latrine and built a screen out of For several of our themes, a big part sticks, grass and leaves. Even once the of the project has been finding out Image courtesy of Locutus Borg farmer had provided portable toilets, about how people fed themselves. we still managed without clean run- This is a great chance for interdiscipli- ning water: for washing hands and food, we took water in canisters; for

Stone Age tool from the Western Sahara desert, Africa

The gantija temple is a Stone Age temple complex on the island of Gozo, Malta. It is more than 5500 years old, making it older than the pyramids of Egypt.

50 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science education projects

Image courtesy of Fir0002; image source: Wikimedia Commons

nary learning, which combines a wide Image courtesy Anja Jonsson; image source: Flickr range of activities that can be tailored to different levels, covering different topics across science and technology. For example, in our Stone Age project, one group activity involved Chamomile learning about hunting. The hunters’ group – which was popular with girls as well as boys – made bows and arrows out of branches and stringw1, and learned how to use them. Having a small forest nearby to gather sticks and branches from was a big help, but of course it would also be possible to Mint A dandelion

provide the raw materials from else- Image courtesy of Project Rastko; image source: Wikimedia Commons where if necessary. This activity offers considerable opportunity for experimentation and Image courtesy of Zeetz Jones; image source: Flickr problem solvingw2. Which kind of wood works best? How thick? How learn more about plants and food. For dry? And how best to shoot the ar- example, one group collected herbs, rows? Is it better to fire upwind or such as chamomile, mint and lemon downwind? Should you aim horizon- balm for infusions. A lot of children

tally or upwards? Do feathers make were not familiar with these, so we General science

Image courtesy of Project Rastko; image source: Wikimedia Commons the arrow fly straighter? The pupils held a tasting session and smelled the spontaneously asked many of these plants before and after steeping in hot questions themselves, but teachers can waterw2. burn well, and how to avoid damag- also help to structure the exercise by Another group gathered edible ing the landscape by using local mate- making suggestions and pointing the leaves such as dandelions to make a rial like sand, earth and water from children in the right direction. salad, which the class ate together. A the stream to tidy up afterwards. It Of course, the companion to hunt- third group gathered wheat grains also plays a role in the final stage of

ing is gathering. We have tried a range from the farmer’s fields, ground them our week on the meadow: inviting Primary of gathering activities in several of our into flour and made flatbreadsw3, the parents to see what their children weeks on the meadow, as a way to testing different cooking methods, have learned. including over an open fire and on hot With this sort of project, safety is stones. obviously an important consideration. As well as contributing to the bread- However with sensible precautions making activity, building a fire is a we have had only one minor accident way of learning about which materials in 10 years. Our meadow is fenced, and we use barrier tape to restrict Image courtesy of Petra Breuer-Küppers Image courtesy of Petra Breuer-Küppers the children to just part of it; pupils who do not stay within the limits of the tape are sent back to school. At all times, each child is part of a group that is the responsibility of one adult. We also take specific precautions depending on the activities. For example, it is vital to correctly identify edible plantsw4, be aware of any local parasites or other health hazards, Investigating what and not to allow the children to eat makes a good bow anything without the permission of Bows made by the children. and arrow. a teacher. Similarly, activities involv-

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 51 Image courtesy of Project Rastko; image source: Wikimedia Commons Image courtesy of Petra Breuer-Küppers demonstrate which ones burn better or less well. The gatherers invite the parents to try the different types of herbs and plants they have collected throughout the week. As well as being a chance to show off what they have learned, this session reinforces learning by enlarging the children’s vocabulary and teaching fires or bows and arrows must be ing them how to present the results of closely supervised. an experiment. At first, we feared this This was the first homemade soup that The precise activities you choose more transparently didactic element some of our pupils had ever tasted. for your project will depend on your of the week on the meadow might theme and on the site you use. We make the activities less fun for the have always strived, however, to children, but in fact it turned out to be include hands-on activities. For in- a source of motivation. Moreover, it The week on the meadow provides stance, the year that our theme was helps broaden the scientific and tech- a flexible framework in which a range horses, we had a real horse that the nical learning of the week by adding a of activities can be anchored, and children could ride and groom, we linguistic dimension. which can be developed and chosen made horses out of wood and cre- The central part of the final day by the teachers and pupils together. ated jewellery for the horse’s mane, to is cooking up a big pot of soup out For instance, in addition to the core name just a few activities. When we of freshly picked vegetables and science content of our week in the used the theme of pirates, the children plants from the meadow and the meadow, we also find time for songs made paper boats and raced them fields – another opportunity to learn and games, handicrafts, and have on the stream, learned how to sword about plants, but also a more general even fitted in a visit from a local bee- fight, played games that involved introduction to healthy eating, and a keeper. It is also an opportunity to boarding other ships, and made pirate shared experience for children, par- bring in outside partners – in our case, clothes and eye patches. ents and teachers. For most of our the farmer, the beekeeper and the lo- Whatever the current year’s theme, pupils, many of whom come from cal scout group – further breaking the on the last day, we set up exhibitions disadvantaged backgrounds, this is routine of classroom learning. of what the different groups have the first time they have tried soup Finally, it represents a holistic way been doing. For example, parents get prepared from fresh ingredients. Over of teaching, combining different to see the bows and arrows, and the the years, we have seen that pupils aspects of science with practical ac- children explain how they are made take the idea of freshly prepared food tivities that have a real impact on the and used. The class presents the dif- back home with them – a perfect ex- children’s lives. ferent types of fuel that they have ample of how practical and theoretical experimented with in the fire, and elements come together. Web references w1 – The Internet offers a wealth of instructions for building bows and arrows of different levels of sophis- tication. The Instructables website offers one example of how to make Image courtesy of Project Rastko; image source: Wikimedia Commons a simple bow and arrow. See Image courtesy of Soerfm; image source: Wikimedia Commons www.instructables.com/id/ How-to-Make-a-Bow-and-Arrow or use the shorter link: http://tinyurl. com/c6wap4w

The Poulnabrone Dolmen is a Stone Age tomb in County Clare, Ireland.

52 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org General science Primary 53 I

Edition. rd Issue 25 : Winter 2012 Winter Issue 25 : I articles for primary

To learn how to use learn how To ? www.scienceinschool.org/ this code, see page 65. Berkeley, CA, USA: Ten Speed Press. Speed Press. CA, USA: Ten Berkeley, ISBN: 978-1580083638 of the Sci- the rest why not browse ence in School school primary has been Petra Breuer-Küppers Woods: An Environmentally Sound An Environmentally Woods: to a Lost Art. 3 Approach Cuevas de las Manos (Spanish for de las Manos (Spanish for Cuevas of of the hands’) in the province ‘cave in artwork The Argentina. Santa Cruz, and 9300 years dates back the cave paint from a spraying created by was hands. bone pipe onto the artists’ If you found this article inspiring, After a schoolteacher for 25 years. physics and music, studying biology, - she worked as a teacher in both main and special-needs schools. stream She is now based at the University for a studying of Cologne, Germany, PhD and teaching university students. in teach- She is particularly interested ing science to primary-school classes, doing experiments and improving language skills. She can be contacted and is at [email protected], happy to give insights or advice to teachers who want to adapt the week on the meadow concept. Meyer K (2011) How to Shit in the Meyer K (2011) Science in School Science in School - Science educationScience projects

Layton, UT, Layton, UT, Playground: Activities, Crafts, and Activities, Crafts, Playground: to Get Games to Encourage Children Outdoors. Chicago, IL, USA: Chicago ISBN: 978-1556527234 Review Press. 101 Things to Do Outdoors Before Up. London, UK: Frances Grow You Lincoln Publishers. ISBN: 978-0711229396 History! Stone Age: Step Back to the Earliest Humans, with 15 of the Time 380 Exciting and Step-by-Step Projects . San Francisco, CA, USA: Pictures Armadillo Books. ISBN: 978-1843229742 . Open Fire Cooking on an Year-Round London, UK: Frances Lincoln Pub lishers. ISBN: 978-0711232815 Plate. Dirt To Foods From USA: Gibbs Smith. ISBN: 978-1423601500 the Grill, and Recipes for Techniques and Camp- Backyard Oven, Fireplace, Speed CA, USA: Ten . Berkeley, fire ISBN: 978-1580089456 Press. Nature’s Schofield J (2007) Nature’s Danks F, Schofield J (2009) Go Wild!: Danks F, C (2012) Hands-On Hurdmann Cook Wild: S (2012) Cook Wild: Fischer-Rizzi Plants: Wild Kallas J (2010) Edible Wild Cooking: Karlin M (2009) Wood-Fired . similar recipe (for chapattis, in (for chapattis, similar recipe Children: The Classic Parents’ & The Classic Parents’ Children: Guidebook. Awareness Nature Teachers’ Dawn Pub- CA, USA: Nevada City, lications. ISBN: 978-1883220730 help you identify herbs, you will need one that describes the plants found in your part of the world. we used a As one of our resources, Wildpflanzen Swiss guide, Essbare website (www. See the Ökoforum or use the direct oeko-forum.ch) link: http://tinyurl.com/78eoqe5 English) is available on the BBC website. See www.bbc.co.uk/food link: http://tinyurl. or use the direct com/3yduntu ised the activities can be download- the Science in School website: from ed www.scienceinschool.org/2012/ issue25/stoneage#resources on the Stockbrot) (Preetzer bread Chefkoch website (in German). See or use the direct www.chefkoch.de link: http://tinyurl.com/cnaxzk6 Sharing Nature with Cornell J (2006) Sharing Nature Resources w4 – When looking for resources to w4 – When looking for resources Image courtesy of Marianocecowski; image source: Wikimedia Commons Wikimedia image source: Image courtesy of Marianocecowski; - details of how we organ w2 – More for flat- used a recipe w3 – We A www.scienceinschool.org Your local meadow might not be local meadow Your as spectacular as this one in New matter USA, but that doesn’t Jersey, that counts! use it you how – it’s

Image courtesy of Nicholas_T; image source: Flickr Image courtesy of Petra Breuer-Küppers of Petra Image courtesy Orthodontists hold the key to a nice smile. Image courtesy of Trypode; image source: Flickr Image courtesy of lanuiop; image source: Flickr

The changing face of orthodontics Many of us have had our teeth straightened with braces. Few people know, however, that orthodontics involves a great deal of fundamental science and fast-moving technology.

By Sophie and Image courtesy of Jenn and Tony Bot; image source: Flickr Georges Rozencweig

ost of us are familiar with orthodontics as a kind of mechanical en- gineeringM inside the mouth – all those metal braces, plates and wires. But how many of us are aware of the different sciences involved in this area of dentistry? Today’s orthodontists have to understand and apply a good deal of specialist science – everything from genetics to metallurgy. achieving a perfect Hollywood smile: As orthodontists, we are always What is orthodontics? our jaws and teeth are used for talking seeking the latest insights and tech- Orthodontics is the branch of den- as well as chewing, so orthodontics is niques from relevant scientific fields tistry concerned with diagnosing and concerned with how facial anatomy and applying them to our work. correcting irregularities of the teeth affects these functions, as well as with In this article we will look at several and jaws. It is used for far more than cosmetic improvements. examples. Some are on the opposite page.

54 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Growth and development: Physics: faces change as they many orthodontic resins mature and age, due to Science topics can be cured (polymerised) alterations in body tissues. using light. Four main types Understanding these of polymerising light source processes allows us to Genetics: are available: halogen bulbs, positively influence we need to be plasma arc lamps, argon ion them. able to diagnose lasers, and light-emitting whether a problem

Ima Biology diodes. ge c has a genetic cause, our tes Metallurgy and y o f J so we can treat it oë l R o materials science: z e n effectively. c w as well as metals, we use e ig alginates and silicones for taking impressions, composites and glass Radiology: ionomer cements for sealing and radiographs help us to sticking, plaster for making casts, diagnosis complex problems. and resins for creating removable We use many different types of appliances. We need to understand radiographs, to provide views from each material’s physical and different angles (frontal, profile or chemical properties to use them panoramic) or exploit different in the best way for imaging techniques (scanners, each patient. magnetic resonance imaging and cone beam computed Physiology: tomography). everyone is different in Biomechanics: Physics precisely how they breathe, we apply the laws chew, swallow and speak. of mechanics to adjust Function and form are closely Microbiology: the position of teeth. We related, so these processes form by teaching our need to ensure that the part of each patient’s diagnosis patients about oral forces resulting from our and treatment plan (figure health and plaque work produce only the 1, page 56). removal, we help movements that are prevent tooth decay needed. and gum disease.

Physics was at university put it, “It’s all connected, you know!” Biology Dentistry is a career many young people choose to Chemistry study at university. However, certainly in UK schools, very little (if any) time is spent studying the mouth, Dentistry teeth or dental science. This article provides excellent Molecular biology reading material for those students who are thinking Genetics and inheritance of a career in dentistry. It could be used by teachers to Transcription and translation provide an introduction to dentistry and its subspecial- Stem cells ties, and to help students make an informed choice about their prospective careers. Properties of metals, alloys, composites, smart materials In addition, the article provides an alternative context Ages 16+ for biology lessons on transcription and translation of DNA, cell signalling and cell differentiation, and toti- Everybody has an experience of visiting the dentist: for potent stem cells. Teachers may wish to use the article some, these visits involve nothing more than a quick as a basis for a group discussion or research project; poke around and a polish; for others, it can be a very alternatively they may wish to recommend it as back- traumatic experience. ground reading material before the commencement of However, to what extent do we understand the role of teaching. For physics and materials science lessons, a dentist? In the UK, all dentists must undergo a 5-year the article also provides an insight into real-life ap- period of study to gain a primary dental qualification. plications of alloys, composites and smart materials. Those who wish to specialise in orthodontics will need In a social context, the article can serve as a basis to both dentistry experience and a further 3-year special- discuss health care in the developing world, using the ist qualification. In addition to clinical training and treatment of cleft palates as an example. practice, the dental student will learn about molecular Jonathan Schofield, McAuley Roman Catholic High biology, anatomy and physiology, materials science School, Doncaster, UK

REVIEW and human disease. As a dental student with whom I

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 55 Genetics and molecular biology way these genes are transcribed can Images courtesy of Sophie and Georges Rozencweig in orthodontics lead to abnormalities in facial development. Some of the problems that ortho- Another example of the importance dontists deal with are genetic in origin of molecular biology to orthodontics (figure 2). Although most of these is the recent discovery that dental are minor, others result from genetic pulp (the area of connective tissue at abnormalities in the way that the head the centre of a tooth) contains valuable and face develop before birthw1. In the adult stem cells, which can be induced embryo, the development of facial to form other types of cells. Thus structures begins with neural crest when a tooth is extracted or falls out, cells forming at the site of the brain. the stem cells may be harvested and These cells then migrate to form a tis- stored for future treatment. Stem cells sue that differentiates into cells called are already being used to treat some osteoblasts, chondroblasts and odon- cancers, and additional applications togenetic cells. These then develop to may be on the horizon. For example, form the hard tissues of the head and researchers are exploring whether neck – the bones, cartilage and teeth. stem cells can be used to grow a natu- During this process, molecules ral replacement for a missing tooth. called signalling factors and transcription factors play an important part. Biomechanics and orthodontics Signalling factors are a cell’s way of triggering a response in another cell, The amount of force needed to while transcription factors control move a tooth depends on its size and which specific DNA sequences are the type of movement (turning or used to produce mRNA and thus sliding). The moving force also needs proteins. For example, we now know Images courtesy of Sophie and Georges Rozencweig that if the signalling factor TGF-b is inactive, this causes cleft palatesw2 and upper jawbone malformations. Mutations in the receptor sites (where Figure 1: the response is triggered) for the sig- These state-of-the-art nalling factor FGF also cause a large braces are almost invis- number of craniofacial abnormalities. ible, even when the wearer smiles, because they are hidden Another example is the transcrip- on the inside of the teeth. In this tion factors associated with the technique, called lingual ortho- homeobox genes. These transcrip- dontics, every brace is custom- tion factors are especially important made to fit the teeth using in enabling the neural crest cells to computer and robotic develop into the skeletal structures technology. of the head and face, so defects in the Public domain image; image source: Wikimedia Commons

Figure 2: Argon ion This patient has lasers are used mandibular progna- to polymerise thism (a protruding orthodontic lower jaw) with a resins. genetic cause.

56 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science topics

Images courtesy of Sophie and Georges Rozencweig Images courtesy of Nissim Benvenisty; image source: Wikimedia Commons Biology Figure 3: We removed this patient’s ankylosed (abnormally rigid) upper left canine and closed the resulting space using a mini-plate. This system enabled us to close the space without shifting the midline of her smile. Human embryonic stem cells. Researchers are investigating whether stem cells can be encouraged to grow into teeth. Images courtesy of Sophie and Georges Rozencweig Physics an anchor, so a group of teeth and appliances are selected and used as anchorage (figures 3 and 4). An X-ray taken after the extraction, Early in the treatment, showing the As orthodontists, our task is to showing the hole where the upper left gap left by the removal of the tooth. decide on the best combination of canine was removed, and the forces and anchorage to achieve the mini-plate that was used to close right movements, without any ad- the gap. verse effects. We review each stage of treatment to make sure this is happening; if it is not, we need to change the treatment plan. In traditional orthodontics, appliances such as headgear and intra-oral elastics are used to reinforce anchor- The gap has been successfully closed. age, which require a good deal of patient co-operation. Today, titanium The result: the first upper left pre- mini-screws can be used instead in molar has been moved forward to Figure 4: some cases (figure 4). replace the missing canine. We removed this patient’s first left lower molar, Metallurgy and orthodontics then closed the gap using a mini-screw as a fixed, temporary The forces used in orthodontics force suitable for the initial anchorage. The spring attaching come from the archwires (figure 5). alignment phases. However, they the mini-screw to the second At the beginning of the treatment, the cannot be soldered. left molar is the active mecha- w3 wires need to be quite elastic to start • Shape-memory alloys : these nism that pulls that tooth individual teeth moving. Later on, the metals have variable elasticity forward. wires have to be more rigid to ensure depending on the temperature. stability while a whole block of teeth They can be bent for insertion into is moved. the mouth; once there, they ‘try’ to Orthodontists can choose wires recover their initial shape, exerting made from a variety of metallic mate- a force on the teeth. rials: class misses a science lesson because • Stainless steel: this is easy to shape A dynamic discipline of an appointment with an ortho- and has high rigidity so it provides As you can see, orthodontists need dontist, don’t worry – it might be the stability. to be good all-round scientists to keep perfect opportunity to learn about the • Nitinol alloys: these nickel-titanium up with the changing knowledge and latest findings in molecular biology, alloys have very high elasticity. technological innovations in their or provide inspiration to a budding They produce a weak but constant discipline. So, if a student in your materials scientist.

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 57 Image courtesy of bluebike; image source: Flickr _braces_work.htm) or a brief history 68. www.scienceinschool.org/2010/ of orthodontics (www.archwired. issue14/chemlight com/HistoryofOrtho.htm). To find out more about how stem cells Another short history of orthodontics can be used in medicine, see: is available on the About.com web- Hadjimarcou M (2009) Review of site (http://inventors.about.com) or Potent Biology: Stem Cells, Cloning, via the direct link: http://tinyurl. and Regeneration. Science in School 11: com/9n2f8cw 92. www.scienceinschool.org/2009/ The Braces Knowledge Base website, issue11/potentbiology also maintained by a braces wearer, Funded by the European Commission, offers comprehensive illustrated the Eurostemcell website offers in- Figure 5: information about orthodontic The archwires formation and educational resources devices. See: www.tanos.co.uk/ are what connect the on stem cells and their impact on braces, acting like an braces/bkb society. See: www.eurostemcell.org engine to guide and move The website of the British Orthodontic If you found this article useful, you the teeth. Without the Society offers information about might like to browse the other wire, the teeth would education and research as well as medicine-related articles in Science never move. careers in orthodontics. See: www. in School. See: www.scienceinschool. bos.org.uk org/medicine Dentistry has a surprisingly long history. Recently, a filling was found in Web references the fossilised jawbone of a man who Sophie and Georges Rozencweig w1 – See a BBC video clip about facial lived 6500 years ago in what is now both trained in orthodontics in Paris, development in the womb. http:// Slovenia. To learn more, see: France, after which they gained mas- youtu.be/wFY_KPFS3LA Bernardini F et al. (2012) Beeswax as ter’s degrees in orthodontics from w2 – This animation shows how a dental filling on a Neolithic human Case University in Cleveland, Ohio, cleft palate develops (voiceover tooth. PLOS One 7(9): e44904. doi: USA. Since 1991, they have shared in Russian). http://youtu.be/ 10.1371/journal.pone.0044904 an orthodontic practice in Grenoble, WAU13syh-w4 PLOS One is an open-access research France. Both Georges and Sophie are in- w3 – The website of the UK’s National journal, so this and all other articles volved in continuing education: they STEM Centre offers a free down- in it are freely available. give university lectures, write articles loadable booklet about metals and Barras C (2012) Oldest dental filling for publication and are on the editori- shape-memory alloys, together with is found in a Stone Age tooth. New al board of several French orthodontic suggestions for teachers on how Scientist. www.newscientist.com or journals. Georges is the editor of the to introduce the ideas in the class- use the direct link: http://tinyurl. journal l’Orthodontie Française. room, plus student activity sheets com/stoneagefilling and notes for teachers and techni- To learn more about how light can be cians. See the National STEM Centre used in polymerisation, see: website (www.nationalstemcentre. Douglas P, Garley M (2010) Chemis- org.uk; ‘Metals and smart alloys’) or try and light. Science in School 14: 63- use the direct link: http://tinyurl. To learn how to use com/8gcagcr this code, see page 65. Image courtesy of ben matthews :::; image source: Flickr Resources A trip to the dentist The Archwired website (www. wouldn’t be com- archwired.com), maintained by an plete without having adult wearer of orthodontic braces, every crevice of your hosts articles on various orthodontic mouth explored with a small circular topics. See: www.archwired.com mirror. For example, how braces work (www.archwired.com/how

58 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org Science topics

Weighing up the evidence: Image courtesy of Stockmonkeys.com; image source: Flickr what is a kilo?

We all know what a kilogram is – or do we? Researchers worldwide are working to define precisely what this Physics familiar unit is.

By Eleanor Hayes and Physics Marlene Rau Chemistry History of science Ages 11-19 ow much does it weigh? What is its surface area? This article highlights the importance of having and using an interna- What is its temperature? tional system of units. It could be very suitable for introductory lessons TheseH questions may seem simple but in physics or chemistry, and could also be used in non-scientific sub- the answers only make sense when jects such as languages and history to explain how important it is to we have defined a value and a unit. follow established conventions (e.g. grammar). The more widely accepted this unit Before reading the text, the following questions could be asked to stu- is, the better the measurements are dents to make them start thinking about the concepts explained in it: understood. Just imagine – if I walked 1. Is it important to have standard measurement units in science? seven furlongs to work this morning 2. When do you think the international system of units was estab- and you travelled 10 km, who had the lished? longest journey? This is why we need an international system of units. 3. What could happen if scientists do not use standard units? The first unit to be internationally 4. Can you find an analogy between the international system of units defined was the metre (figure 1, page and a concept in a non-scientific subject such as English, history 60). It also led to the first international or art? agreement on units, when the 1875 As the article includes some historical data of the evolution of the Convention of the Metre in Paris, international system of units, it could be used for a discussion of the France, established the International history of science, a topic rarely seen in secondary school. Moreover, Bureau of Weights and Measures these historical details could make students who are not usually keen (BIPM, or Bureau International des Poids on science read the article with interest. et Mesures) – an organisation that ex-

REVIEW Mireia Güell Serra, Spain ists to this day. www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 59 newton yard furlong lux kilogram hertz newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela second joule ampere kelvin volt candela becquerel mole miles pint degrees fahrenheit becquerel mole miles pint degrees fahrenheit newton yard furlong lux kilogram hertz newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela second joule ampere kelvin volt candela becquerel mole miles pint degrees fahrenheit becquerel mole miles pint degrees fahrenheit newton yard furlong lux kilogram hertz newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela second joule ampere kelvin volt candela becquerel moleImage courtesy of milesthe National Institute of Standardspint and Technology; degrees image source: Wikimedia Commonsfahrenheit Imagebecquerel courtesy of clipart.com mole miles pint degrees fahrenheit

Figure 1: The international prototype metre bar, made of an alloy of platinum Figure 2: The international prototype of the and iridium. This bar embodied the international definition of a metre from 1889 kilogram: a cylinder of platinum-iridium al- to 1960. loy, 39 mm high and 39 mm in diameter

Initially, the only common units countries, the BIPM now has 55 mem- the prototype and its copies can now were for length and mass, but the ber states. Nonetheless, the degree to be compared with very high precision system has evolved over the years. which the SI has been adopted varies (up to 1 microgram), revealing signifi- Thus the initial set of units for length between the members. In both the cant variation (figure 3, page 61). and mass was extended to include the UK and the USA, for example, miles, It is, therefore, high time for an ab- standards of electricity, photometry pints, and degrees Fahrenheit are still solute definition of the kilogram. This and radiometry, ionising radiation, commonly used. Furthermore, even in will not involve changing the mass of time and chemistry. The complete set fully metrified countries, some non-SI the kilogram. What will change is the of standardised units is referred to as units remain popular. These include way in which the kilogram is defined: the International System of Units (SI the minute, day and hour, as well as w1 for Système International d’Unités) . the hectare, litre and tonne. Image courtesy of the Swiss Federal Institute of Metrology METAS The SI is based on the metric system and consists of both base units and The case of the kilogram derived units. The seven base unitsw2 The kilogram is the only one of define a system of independent the seven base units to have a prefix quantities and their units (see box on (‘kilo’) in its name. It is also the only page 61). The derived units of the SI one that is still officially defined by define all other quantities in terms a material artefact – all others are of the base units. For example, the SI defined by fundamental constants or unit of force, the newton, is defined as atomic properties (see box on page the force that accelerates a mass of one 61). The international prototype of the kilogram at the rate of one metre per kilogram is a cylinder of platinum- second squared. iridium alloy, machined in 1878 and Even in a vacuum where there are rela- preserved at BIPM (figure 2). tively few atmospheric gas molecules, some of them will adsorb to the surface A universal system? Over the years, several official cop- of a prototype kilogram, adding to its A universal set of units has clear ies have been produced and distrib- weight. By using two prototypes, each advantages, but there is still some way uted to various national metrology of- with the same volume but different sur- to go before the SI is established glob- fices (metrology is the scientific study face areas, scientists can account for the ally and to the exclusion of all other of units and measurement). With the contribution that adsorbed gas molecules systems. Initially established by 17 aid of modern technology, the mass of make to a prototype’s weight.

60 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela becquerel mole miles pint degrees fahrenheit newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela becquerel mole miles pint degrees fahrenheit Science topics newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela becquerel mole miles pint degrees fahrenheit

The definitions of the SI base units

Base quantity Base unit Definition according to the International Committee Date of the of Weights and Measures (CGPM) current definition

The length of the path travelled by light in a vacuum Length Metre (m) 1983 during a time interval of 1/299 792 458 of a second

Mass Kilogram (kg) The mass of the international prototype of the kilogram 1901

The duration of 9 192 631 770 periods of the radiation Time, duration Second (s) corresponding to the transition between the two hyper- 1967/68 fine levels of the ground state of a caesium-133 atom Physics That constant current which, if maintained in two straight parallel conductors of infinite length, of neg- Electric current Ampere (A) ligible circular cross-section, and placed 1 m apart in 1946 vacuum, would produce between these conductors a force equal to 2 x 10-7 newton per metre of length

Thermodynamic The fraction 1/273.16 of the thermodynamic tempera- Kelvin (K) 1967/8 temperature ture of the triple point of water

The amount of substance of a system which contains as Amount of Mole (mol) many elementary entities as there are atoms in 0.012 kg 1971 substance of carbon-12

The luminous intensity, in a given direction, of a source Luminous that emits monochromatic radiation of frequency 540 x Candela (cd) 1979 intensity 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian BACKGROUND Image source: Wikimedia Commons rather than being defined as the mass of an object stored in a Paris vault, it will be a reproducible definition based on atomic properties and fundamental constants. Using this new definition, a well equipped laboratory will be able to create from scratch, without refer-

ence to the prototype, an object that D m ( g) weighs exactly 1 kg. Or, of course, to test and calibrate scales very precisely. Furthermore, redefining the kilogram will also affect three other base units: the ampere, the mole and the candela, the definitions of which de- Year pend on the kilo (see box above). Since the 1990s, several approaches Figure 3: A graph of the relative change in mass of selected kilogram prototypes have been pursued, two of which (from Girard, 1994)

www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 61 Image courtesy of CSIRO; image source: Wikimedia Commons Figure 4: One of the scientists at the Australian Centre for Precision Optics holding a 1 kg silicon sphere for the Avogadro project, an international collaboration to define the kilogram. This sphere is one of the roundest man-made objects in the world.

Strict rules govern the way in which scientists can handle the platinum-iridium mass prototypes. Image courtesy of the Swiss Federal Institute of Metrology METAS

seem promising. Both involve de- the number of atoms in 0.012 kg of high-purity and almost perfect single fining the kilogram in terms of an carbon-12. Thus if we rearrange the crystals can be produced. invariant natural quantity: in one case equation, we could define a kilogram The scientists are using a variety of the Avogadro constant, in another, the as the mass of an Avogadro number of techniques to determine the distance Planck constant. Both of the approach- carbon-12 atoms x 1000 / 12. between atoms (the lattice parameter), es also involve measuring the relevant To do this, the project team aims to the crystal density and the mean mo- constant to an unprecedented degree measure the value of the Avogadro lar mass of the silicon (which has sev-

of precision. constant (NA , which has the same nu- eral isotopes). Using these data, they merical value as the Avogadro num- will be able to calculate the number of Defining the kilogram in terms of ber, expressed in moles) more pre- atoms in the 1 kg silicon sphere and the Avogadro constant cisely than ever before. At the heart of derive a new and more precise meas- The aim of the international Avoga- the project is a nearly perfect sphere urement of the Avogadro constant. dro project is to define the kilogram of silicon (figure 4) weighing exactly This could then be used in a new as the mass of a specific number of 1 kg, as defined by the platinum- definition of the kilogram (Andreas et carbon-12 atoms. Under the current iridium prototype. Silicon, rather than al., 2011; Becker et al., 2003): definition, Avogadro’s number is carbon-12, was chosen because large, 1 kg = atomic mass of C-12 x 0.0012 x NA

An Egyptian cubit rod, used for measuring length. The Egyptian cubit – like all cubits, based on the length of a forearm – was divided into 7 palms of 4 digits each.

Image courtesy of Bakha; image source: Wikimedia Commons newton yard furlong lux kilogram hertz newton yard furlong lux kilogram hertz www.scienceinschool.org second62 I Sciencejoule in School ampereI Issue 25 : Winter 2012 kelvin volt candela second joule ampere kelvin volt candela becquerel mole miles pint degrees fahrenheit becquerel mole miles pint degrees fahrenheit Science topics

above, therefore, precisely measuring More about CERN the Parisian kilogram prototype – as will be possible with the watt balance – will allow h to be measured more The European Organization for Nuclear Re- precisely than before. Once that value search (CERN)w7 is one of the world’s most prestigious is fixed, the kilogram can then be de- research centres. Its main mission is fundamental physics fined in terms of h, m and s, indepen- – finding out what makes our Universe work, where it came dently of the original prototype. from, and where it is going. Worldwide, several metrology CERN is a member of EIROforumw8, the publisher of Science in School. institutes are working to develop increasingly precise watt balances. See all CERN-related articles in Science in School: One project, led by the Swiss Fed- www.scienceinschool.org/cern eral Institute of Metrology (METAS), includes CERN (see box to the left), which is developing a type of mag- Currently, the Planck constant has net that is crucial to the operation of Defining the kilogram in terms of w3 Physics the Planck constant been measured to be: the balance . The aim of all the watt h = 6.626 068 96 x 10-34 kg m2 s-1 balance projects is to reach a new The other approach to defining the The values of fundamental con- definition of the mass unit – known kilogram uses a watt balancew3, w4. stants, such as the Planck constant, are provisionally as the electronic kilo- The watt balance, which compares invariants of nature. However their gram – by reducing the uncertainty in mechanical and electrical energy, was numerical values (e.g. 6.626 068 96 x their experimental setups to ≤ 5 x 10-8. invented in 1975 and used in the 1980s 10-34) depend on the units (e.g. kg, m, This, however, is no mean feat, due to better determine the Planck con- and s) in which they are expressed. to the precision of the measurements stant by weighing the platinum-irid- Fixing the numerical value of the con- and complexity of the instruments ium prototype of the kilogram. Then stant therefore defines the units. In the required. scientists realised they could turn the case of the Planck constant, the metre idea around and use the instrument to and second are already defined in The outlook define the kilogram. the SI. As can be seen in the equation So which of the two approaches will be used to redefine the kilogram? At The watt balance built by METAS to perform previous measurements of the Planck the BIPM’s 24th general conference on constant. A new balance is currently under development. weights and measures in 2011, it was proposed that the definition based on the Planck constant should be used. Nonetheless, if the proposal were accepted, the work on the Avogadro constant would not go to waste. For one thing, the Avogadro constant may be used in a new definition of the molew5. And for another, the Avoga- dro constant provides an alternative method to determine the Planck con- stantw6 – thus indirectly feeding into the definition of the kilogram. But that is another story.

Acknowledgement Image courtesy of the Swiss Federal Institute of Metrology METAS Image courtesy of the Swiss Federal The authors would like to thank Simon Anders, a physicist based at the European Molecular Biology Labora- tory, for his helpful comments on the article. newton yard furlong lux kilogram hertz newton yard furlong lux kilogram hertz www.scienceinschool.org second joule ampere kelvin volt candela second jouleScience ampere in School I Issue 25 : Winterkelvin 2012 I 63 volt candela becquerel mole miles pint degrees fahrenheit becquerel mole miles pint degrees fahrenheit newton yard furlong lux kilogram hertz newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela second joule ampere kelvin volt candela becquerel mole miles pint degrees fahrenheit becquerel mole miles pint degrees fahrenheit newton yard furlong lux kilogram hertz newton yard furlong lux kilogram hertz second joule ampere kelvin volt candela second joule ampere kelvin volt candela Image courtesy of the Swiss Federal Institute of Metrology METAS becquerel mole miles pint degrees fahrenheit becquerel mole milesw8 – EIROforum pint is adegrees collaboration fahrenheit between eight of Europe’s largest inter-governmental scientific research organisations, which combine their resources, facilities and expertise to support European science in reaching its full potential. As part of its education and outreach activities, EIROforum publishes Science in School. To learn more, see: www. eiroforum.org

Resources If you enjoyed this article, you may like to browse the other physics articles in Science in School. See www. scienceinschool.org/physics A mass prototype is getting a thorough clean in low pressure plasma.

References w4 – Visit the BIPM website for more Dr Eleanor Hayes is the editor-in- Andreas B et al. (2011). Counting the details of the watt balance: www. chief of Science in School. She studied atoms in a 28Si crystal for a new kilo- bipm.org/en/scientific/elec/watt_ zoology at the University of Oxford, gram definition. Metrologia 48(2): S1- balance UK, and completed a PhD in insect 13. doi: 10.1088/0026-1394/48/2/ w5 – To learn more about how the ecology. She then spent some time S01 kilogram and the mole may be rede- working in university administration before moving to Germany and into Becker P et al. (2003) Determination fined, see resolution 1 of the BIPM’s th science publishing in 2001. In 2005, of the Avogadro constant via the 24 general conference on weights she moved to the European Molecular silicon route. Metrologia 40: 271-287. and measures in 2011. www.bipm. Biology Laboratory to launch Science doi: 10.1088/0026-1394/40/5/010 org/en/si/new_si/what.html w6 – Learn more about the interna- in School. Girard G (1994) The third periodic Dr Marlene Rau was born in Germa- verification of national prototypes tional Avogadro project. www.bipm. org/en/scientific/mass/avogadro ny and grew up in Spain. After obtain- of the kilogram (1988-1992). ing a PhD in developmental biology at w7 – More information about CERN: Metrologia 31: 317-336. doi: 10.1088/ the European Molecular Biology, she www.cern.ch 0026-1394/31/4/007 studied journalism and went into science communication. Since 2008, she Web references has been one of the editors of Science w1 – The definitive international in School. reference on the SI is published in Image courtesy of Arthena; image source: Wikimedia Commons French, although an English translation is also available. Both versions can be found on the BIPM website: www.bipm.org/en/si/si_brochure

w2 – Learn more about the seven base The flow of sand in an units of the SI system. See: www. hourglass was one way bipm.org/en/si/base_units in which people used to w3 – From the Science in School measure time. You may use one today to time how website (www.scienceinschool.org long to boil an egg. /2012/issue25 /metrology# resources), you can download an explanation of the watt balance (in Word ® or as a PDF). To learn how to use this code, see page 65.

64 I Science in School I Issue 25 : Winter 2012 www.scienceinschool.org newton yard furlong lux kilogram hertz

second joule ampere kelvin volt candelaPublisher: EIROforum, Safety note EIROforum www.eiroforum.org For all of the activities published in Science in Science in SchoolScience is published and topicsfunded by becquerel mole miles pint degrees fahrenheitEditor-in-chief: Dr Eleanor Hayes, School, we have tried to check that all recognised EIROforum, a collaboration between eight of hazards have been identified and that suitable European Molecular Biology Laboratory, Europe’s largest inter-governmental scientific precautions are suggested. Readers should be aware, research organisations, which combines the re- Germany newton yard furlong lux kilogram hertz however, that errors and omissions can be made, sources, facilities and expertise of its member or- Editor: Dr Marlene Rau, and safety standards vary across Europe and even ganisations to support European science in reaching second joule ampere kelvin volt candela European Molecular Biology Laboratory, within individual countries. its full potential. See: www.eiroforum.org Germany Therefore, before undertaking any activity, readers CERN should always carry out their own risk assessment. becquerel mole miles pint degrees fahrenheitEditorial board: The European Organization for Nuclear Research In particular, any local rules issued by employers or (CERN) is one of the world’s most prestigious Dr Giovanna Cicognani, education authorities MUST be obeyed, whatever is research centres. Its main mission is fundamental Institut Laue-Langevin, France suggested in the Science in School articles. physics – finding out what makes our Universe work, Dr Dominique Cornuéjols, European Unless the context dictates otherwise, it is assumed that: where it came from, and where it is going. See: Synchrotron Radiation Facility, France · Practical work is carried out in a properly www.cern.ch Monica Talevi, European Space Agency, equipped and maintained science laboratory EFDA-JET the Netherlands · Any electrical equipment is properly maintained The Joint European Torus (JET) investigates the Dr Rolf Landua, European Organization for · Care is taken with normal laboratory operations potential of fusion as a safe, clean, and virtually Nuclear Research (CERN), Switzerland such as heating limitless energy source for future generations. It can create the conditions (100-200 million °C) in the · Good laboratory practice is observed when Dr Dean Madden, National Centre for plasma sufficient for fusion of deuterium and tritium chemicals or living organisms are used Biotechnology Education, University of nuclei to occur – and it has observed fusion power Reading, UK · Eye protection is worn whenever there is any to a maximum of 16 MW. As a joint venture, JET is recognised risk to the eyes Dr Petra Nieckchen, European Fusion collectively used by more than 40 European fusion Development Agreement, UK · Pupils and / or students are taught safe techniques laboratories. The European Fusion Development for activities such as handling living organisms, Agreement (EFDA) provides the platform to exploit Dr Douglas Pierce-Price, European Southern hazardous materials and equipment. JET, with more than 350 scientists and engineers Observatory, Germany Credits from all over Europe currently contributing to the JET Lena Raditsch, European Molecular Biology Science in School is a non-profit activity. Initially programme. See: www.efda.org/jet Laboratory, Germany supported by the European Commission, it is now EMBL Dr Fernand Wagner, European Association for funded by EIROforum. The European Molecular Biology Laboratory (EMBL) Astronomy Education, Luxembourg Disclaimer is one of the world’s top research institutions, dedicated to basic research in the life sciences. EMBL Copy editor: Dr Caroline Hadley Views and opinions expressed by authors and advertisers are not necessarily those of the editors or is international, innovative and interdisciplinary. Composition: Nicola Graf, publisher. 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Its mission is to shape the develop- With very few exceptions, articles in Science in ment of Europe’s space capability and ensure that Print version: 1818-0353 School are published under Creative Commons investment in space continues to deliver benefits Online version: 1818-0361 copyright licences allow the text to be reused non- to the citizens of Europe and the world. commercially. Note that the copyright licences refer See: www.esa.int Cover images: to the text of the articles and not to the images. 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www.scienceinschool.org Science in School I Issue 25 : Winter 2012 I 65 ns mo om C ia The mystery of altruism d e

im k i

Does true altruism exist? And can science provide the answer? u

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By Oren Harman k

fitness, why do we find altruistic acts Biological altruism is defined by the g y e s

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wherever we look in nature? Consider result of an action: if an amoeba acts u he origin of kindness is a the honey-pot ants of the Ameri- in such a way as to reduce its own fit- mystery. Where do giving can deserts, hanging upside down ness while providing a fitness benefit and altruism come from? like great big pots of sugared water, to another, it is an altruist. (Certain TWere they inherited on the wings of perennially, waiting to be tapped by species of social amoeba are known to natural selection – a gift bestowed the queen and her brood when they sacrifice themselves for their breth- upon us via the inching, evolutionary are thirsty; or gazelles, conspicuously ren.) Human, or psychological altru- march of sacrificial amoeba, selfless jumping up and down to signal to the ism, on the other hand, is all about penguins and charitable baboons? Or troop that a lion lurks in the grass; intent: if I help an old lady cross the is altruism a unique refinement, a sin- or, for that matter, yellow jewelweed gular human triumph over ‘nature red plants (Impatiens pallida), which, when in tooth and claw’? Charles Darwin sunlight becomes scarce, do not hog it Commonly referred to as slime mould, called this the greatest single riddle, by investing in the creation of leaves, Dictyostelium discoideum is a soil- and thinkers ever since have tried to but rather invest in stems and roots so living amoeba. When starved, the normally free-living cells aggregate into a crack it. as to share the sunlight with every- ‘slug’, consisting of viable spores and Here is the mystery: if evolution is one. These are just a few of thousands an altruistic, non-reproducing stalk. a process of survival of the fittest, and of examples from across the natural altruism is a behaviour that reduces world.

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Why is altruism considered to be a behaviour that reduces fitness that reduces to be a behaviour is altruism considered Why organism? for the individual that true altruism does not exist in humans. Some people believe is this? Why selection. a role in natural that could play Altruism is a behaviour idea. Use a specific example to support this really never mathematics, it was ‘If altruism could be explained by this means. Explain what it seemed.’ what y Biology Ages 15+ s

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Altruism is a behaviour observed in all types of organism, yet its causes in all types of organism, yet observed Altruism is a behaviour the plausible In this article, Oren Harman explores remain a mystery. in humans. true altruism exists whether causes of altruism and be used just as is not a science article in the strict sense; it could This as the article could use the Teachers a social studies lesson. easily in topics that link science and social studies basis of a discussion of many selection and altruism; the genetic basis subjects: for example, natural the group; and mathematical of altruism; altruism and the fitness of age group article could be used for any The formulations for altruism. in particular those aged 15-19. students, of secondary-school with potential article could be used in a comprehension exercise, The questions including: 1. 2. 3. 4. e g

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How can altruistic behaviour such as a soldier jumping on a grenade to save his comrades be explained scientifically? One scientist who tried to solve the mystery of altruism was the US

Image courtesy of Rolf Unterberg; image source: Wikimedia Commons population geneticist George Price. ductive cost to the individual per- Deriving an equation in the late 1960s forming the altruistic act (Hamilton, that would later carry his name, Price 1964a, 1964b). Does this mean that it came to believe that if altruism could is natural to help kin, but unnatural to be explained by mathematics, it was help strangers? not true altruism. Selflessness was Perhaps not. Another explanation is always interested – this is what he be- simple reciprocation: one individual lieved his equation seemed to indicate should help another in the expectation (Price, 1970). of being helped in return. Related to For George Price, this was a terrible this is the matter of trust: if I cannot realisation and he descended on the signal to others that I can be trusted, I homeless people of London, UK, like won’t survive in a world that depends an angel, determined to disprove the Albert Schweitzer (1875-1965) won on co-operation. very maths that he had constructed. the Nobel Peace Prize in 1952 for his A third explanation is group selec- In the end, having given away all his philosophy of ‘reverence for life’. tion: those groups that use altruism possessions, he became a homeless as a social glue to help to cement derelict himself, committing suicide in cohesion will outcompete groups of a cold London squat in 1975. which ought to be; or, what we ob- non-co-operative individuals. Science is a powerful tool for un- serve in nature with a rule for our But do these explanations leave derstanding the world. Neurogenetics own behaviour (Hume, 1739). This is room for true altruism? The explana- and functional magnetic resonance important when it comes to altruism, tions satisfy the sceptic, as they all imaging studies are attempting to find because in the years since Darwin, ultimately hinge on the logic of ego- the genes for altruism and the particu- science has provided a number of tism: it’s worth helping others or even lar regions of the brain that play a role explanations for the evolution of sacri- the group if it benefits yourself. And in altruistic behaviour (Churchland, ficial traits. if that is what models and theories 2011). But precisely because of this, we One of these explanations is nepo- show, supported by empirical obser- need to remember the fate of George tism: the closer the genetic related- vation, then perhaps true altruism is Price: his story is a personification ness, the greater the chance of altru- really just a dream. More dangerous of the very paradox of altruism. It ism. This was formalised in algebra by still is the idea that if we evolved to

the late British evolutionary biologist be altruistic only for selfish reasons, Commons Wikimedia Image courtesy of Ltshears; image source: Bill Hamilton, who stated that a ge- perhaps we shouldn’t even attempt to netic trait for altruism should spread behave as true altruists. through a population if: rB > C where r is the genetic relatedness of the two individuals, B is the reproduc- Naked mole rats are sometimes referred to as the social insects tive benefit gained by the recipient of of the mammal world. the altruistic act, and C is the repro-

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To find out why psychologist Steven Pinker does not support the idea

Image courtesy of Evert Odekerken; image source: Wikimedia Commons of group selection, see his essay NY, USA: W.W. Norton. ISBN: ‘The false allure of group selection’. 9780393067781 http://edge.org/conversation/ Hume D (1739) A Treatise on Human the-false-allure-of-group-selection Nature. Cheapside, UK: John Noon If you found this article interesting, The text is freely available online Mother Teresa of Calcutta you may like to browse the other (1910-1997) won the Nobel via Project Gutenberg. See: www. biology-related articles in Science in Peace Prize in 1979 for serving gutenberg.org/ebooks/4705 School. See www.scienceinschool. the poorest of the poor. Price GR (1970) Selection and co- org/biology variance. Nature 227: 520-521. doi: 10.1038/227520a0 shows that the tools of science are Download the article free of charge Oren Harman is a writer and profes- not always relevant to the kinds of on the Science in School website sor of the history of science. He stud- questions we are interested in, such as (www.scienceinschool.org/2012/ ied history and biology at the Hebrew how we should behave. If we are able issue25/altruism#resources), or University in Jerusalem, Israel. After a to answer all the scientific questions subscribe to Nature today: www. master’s degree and a doctorate from we can pose, will it explain everything nature.com/subscribe Oxford University, UK, he spent two that we want to understand? George years at Harvard University, USA, in Price’s story demonstrates that the Web reference the department of history of science. answer to this question is ‘no’. w1 – This article is based on an article Oren is currently a professor of sci- by Oren Harmanw1 on the Forbes ence, technology and society at Bar Acknowledgement website (www.forbes.com). See the Ilan University, Israel, and chair of the This article was adapted from a direct link: http://tinyurl.com/ graduate programme there. He focus- w1 previous article by Oren Harman , orenharman es on the history and philosophy of published on the Forbes website. Also on the Forbes website, watch modern biology, evolutionary theory, the evolution of altruism, 20th century References a video of Oren Harman discussing the story behind his latest book, genetics, and historical biography. Churchland P (2011) Braintrust: What The Price of Altruism. http://video. As a writer, Oren has contributed to Neurobiology Tells Us About Morality. forbes.com/fvn/booked/ The New Republic, Science, Nature, The Princeton, NJ, USA: Princeton Uni- price-of-altruism New York Times, The Times, the Times versity Press. ISBN: 9780691137032 Literary Supplement, the New York Hamilton WD (1964a) The genetical Resources Review of Books, the Economist, Forbes, evolution of social behaviour. I. Jour- Philosopher Elliott Sober and biologist The Huffington Post and many others. nal of Theoretical Biology 7(1): 1-16. David Sloan Wilson attempt to rec- He used George Price’s story in his doi: 10.1016/0022-5193(64)90038-4 oncile altruism, both evolutionary book The Price of Altruism (Harman, 2010) to illustrate 150 years of efforts Hamilton WD (1964b) The genetical and psychological, with the scien- to find the origins of kindness. The evolution of social behaviour. II. tific discoveries that seem to portray book won the 2010 Los Angeles Times Journal of Theoretical Biology 7(1): 17- nature as ‘red in tooth and claw’. Book Prize. 52. doi: 10.1016/0022-5193(64) Sober E, Wilson DS (1998) Unto 90039-6 Others: The Evolution and Psychology Harman O (2010) The Price of Altru- of Unselfish Behavior. Cambridge, ism: George Price and the Search for MA, USA: Harvard University the Origins of Kindness. New York, Press. ISBN: 978-0674930476 www.scienceinschool.org Science in School I Issue 25 : Winter 2012 Winter 2012 Issue 25 How many schools and teachers do you reach – The European journal for science teachers worldwide? In this issue: Accelerating the pace of science: interview with CERN‘s Rolf Heuer Also:

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