questions 1. 1

1. List ten ways that you have used science 5. Make a cartoon strip or poster about one of today. the things you listed in question 1. 2. List ten things that you could not have 6. In a small group create a play or write a song done without scientists creating or making about using scientifi c skills in your everyday discoveries. life. Perform this for the class. 3. Which of the following are observations and 7. Look through a newspaper or magazine or which are inferences? Present your answers browse the Internet to fi nd an article that in a table. discusses scientifi c methods. Cut out or Aaron is 168 cm tall. print out the article and paste it into your The bushfi re was caused by lightning. workbook. Explain to your class what the Steven is stronger than David. article is about and what will be its benefi ts The population of Darktown is 1.2 million. or problems. Lanah’s cat weighs 2 kg. 8. Find some examples of how scientists use Jaimie is a faster runner than Soula. models. Explain what the model is for and 4. Every branch of science has a special name. how it helps our understanding. Can you match the names below with what they study?

acarology fungi oology fruit anemology snakes ophiology mountains bryology clouds orology reptiles and amphibians dendrochronology wind palynology ants herpetology mouth disorders pomology rivers mycology fossil pollen potamology age of trees by rings myrmecology birds’ eggs pteridology mosses nephology fermentation stomatology dreams nosology ferns trichology classifi cation of diseases oneirology hair zymology mites and ticks

11.2.2 Working safely

A science laboratory is a place where you can carry out scciifiilele investigations and conduct experiments. You have already learned that everybody can be a scientist and science is used all Experiments are carefully around us every day. So there are many places that can be called planned step-by-step practical activities, which can be science laboratories, not just your school laboratory or a research recorded and reported in many laboratory at a university, hospital or factory. different ways. A laboratory can be a source of accidents. So wherever your science laboratory is located it is essential that there are rules for your safety. Always ensure that you think before you act so that you don’t endanger yourself or others.

6 Science 8: A Contextual Approach

001_HQSP8_SI.indd1_HQSP8_SI.indd 6 112/5/062/5/06 33:48:25:48:25 PMPM SCIENCE work Activity 1.4 Recognising some science equipment What you need • Bunsen burner • test-tube brush • spatula • gauze mat • boss head and clamp • evaporating dish • test-tube • test-tube rack • watch-glass • fi lter funnel • test-tube holder • heatproof mat • measuring cylinder • tripod • pipe clay triangle • dropping pipette • tongs • stirring rod • retort stand • beaker • conical fl ask What to do 1. Divide the class into groups of two or three students. 2. Your teacher will give each group three pieces of equipment plus nine blank cards or pieces of paper. 3. The task for each group is to prepare a set of three cards for their equipment—‘equipment name’, ‘scientifi c drawing’, and ‘what it is used for’. 4. Each group presents their cards to the class and answers any questions about their equipment. 5. Cards can then be swapped between groups and used for matching activities.

The Bunsen burner scciifiilele In a laboratory many experiments require heat. A Bunsen burner is often used to provide heat, and it is important that you are able to use it safely. Robert Wilhelm Bunsen did not actually invent the Bunsen burner At the top of the Bunsen —he just improved it. He made burner this mixture of gas and air can be much greater contributions to ignited to produce a areas of chemistry such as organic Opening and closing the air hole barrel flame, which is used to chemistry, arsenic compounds, changes the amount of air mixing heat substances. with the gas and so allows you to gas measurements and analysis, control the amount of heat the galvanic battery, elemental produced by the Bunsen burner. spectroscopy and geology. The amount of heat As gas moves into the Bunsen burner produced by the burner from the gas tap, air moves into the collar can be controlled by barrel of the burner through the air turning the metal ring or hole and mixes with the gas. collar at the bottom of the barrel. rubber tubing gas supply The base of the Bunsen burner can get very hot so the burner should Figure 1.7 always be used on a How does the Bunsen burner work? base heatproof mat.

Steps for using a Bunsen burner: 1. Always use a heatproof mat. 2. Connect the gas tube to the gas outlet. 3. Close the air hole before lighting. 4. Hold a lit match beside the mouth of the barrel. Turn on the gas and move the match over the barrel to light the gas. 5. Open the air hole slowly. Set the air hole and gas for the fl ame required.

8 Science 8: A Contextual Approach

001_HQSP8_SI.indd1_HQSP8_SI.indd 8 112/5/062/5/06 33:48:31:48:31 PMPM SCIENCE work Using a Bunsen burner EXPERIMENT 1.5 Aim To learn to use a Bunsen burner safely. Materials • Bunsen burner • platinum or nichrome wire • matches • test-tube • heatproof mat • test-tube holder Method: Lighting the Bunsen burner 1. Your teacher will demonstrate how to use a Bunsen burner. You may need to write some notes or draw some diagrams. 2. Connect your Bunsen burner to the gas tap. 3. Close the air hole by turning the collar. 4. Hold a lighted match at the top of the barrel towards the side of the opening. 5. Turn the gas tap to the fully open position and move the match over the barrel to light the gas. 6. Note the appearance of the fl ame. This fl ame is called a safety fl ame. 7. Using the test-tube holder, hold the test-tube near the top and place the bottom of the test-tube into the fl ame. Observe the deposit that forms on the test-tube. Record your observations in your book. 8. Place the test-tube into the test-tube rack so that your bench is not damaged. Remember, it will be hot! 9. Slowly turn the collar of the Bunsen burner until the air hole is fully open. As you do so, working scientifically observe and report the changes in: (a) the amount of light and heat given off 01

(b) the colour of the fl ame (c) the size of the fl ame.

Results and discussion Draw a fl ow chart showing the steps involved in lighting and using a Bunsen burner.

Include any safety rules. chapter

questions 1.2

1. Think about two laboratory safety rules you 2. Many chemicals can stain, irritate or burn consider important. the skin and some are poisonous. Many (a) Share your rules with a partner and make chemicals are only safe if used correctly. up a list of fi ve rules. What should you do in each of the situations (b) With your partner, decide on how you will listed below? share your rules with the rest of the class. (a) You spill a solid powder. Some ways to present your rules are as a (b) You spill a liquid. rhyme, song, rap or role play. (c) You break some glassware. (c) Swap your list with another pair and (d) Your experiment is fi nished. evaluate their rules.

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001_HQSP8_SI.indd1_HQSP8_SI.indd 9 112/5/062/5/06 33:48:33:48:33 PMPM 3. Why is it important that you let your teacher know if there has been an accident or breakage in the science laboratory? 4. Some chemical bottles have warning labels on them. So do some household substances. At home try to fi nd some of these warning labels and sketch what they look like, or design your own warning label for the following: (a) a poisonous substance (b) a fl ammable substance (c) a corrosive substance. Figure 1.8 How many pieces of science 5. Name the item(s) of science equipment that equipment can you fi nd? can be used to: (a) mix large amounts of liquids together 8. Why should you never point the mouth of a (b) heat small amounts of liquid test-tube towards yourself or others when (c) measure small volumes of liquid heating it? (d) hold test-tubes 9. Describe one piece of science equipment as carefully and accurately as you can without (e) support equipment naming it. See if your partner can identify it. (f) heat small amounts of solids. 10. Write your own ‘dangerous laboratory There are two different fl ames on the Bunsen 6. drama’. Perform your play and ask the other burner. Draw them both and explain when students to list any dangers shown in your you would use each one. play. Watch the dramas by other students 7. Can you fi nd the ten pieces of science and make a list of their dangers. equipment in the puzzle in fi gure 1.8? Draw 11. Create a multimedia presentation or movie each piece separately into your book and to explain how different pieces of science label it. equipment can be used in a laboratory.

11.3.3 Microscopes and magnification

There are many things in our environment that we cannot see without help. We use telescopes to help us see things that are far away such as the planets and details of the surface of the Moon. We use microscopes to see objects that are very small. Light microscopes and electron microscopes provide the images that you will see most commonly. Microscopes and other magnifi ers contain lenses that allow light to pass through them, but bend the light rays so that we can see things more clearly.

10 Science 8: A Contextual Approach

001_HQSP8_SI.indd1_HQSP8_SI.indd 1100 112/5/062/5/06 33:48:34:48:34 PMPM Figure 1.9 Human eyesight is limited. We need instruments to help us see the detail of structures that are far away or very small. We use different types of lenses to carry out different functions.

Light microscopes working scientifically There are many different types of light microscope. Some have only one eyepiece for you to look through. These are called monocular 01 microscopes. Others with two eyepieces are called binocular microscopes. For the microscope to work properly, light must be able to pass through the object (or specimen) you are looking at and then through a selection of lenses. The lenses magnify the specimen being studied. The microscope is focused by changing the distance between the lenses and the specimen. The specimen must be very thin. Special cutting tools chapter are used to cut these thin sections. Sometimes specimens are stained with a dye to make certain features easier to see. You will probably use a microscope like the one in fi gure 1.10.

HUMANEYE

EYEPIECELENS

OBJECTIVELENS

Game SPECIMEN

CONDENSORLENS Figure 1.10 The diagram shows how the LIGHTSOURCE parts of a microscope are organised. 11

001_HQSP8_SI.indd1_HQSP8_SI.indd 1111 112/5/062/5/06 33:48:36:48:36 PMPM SCIENCE work Activity 1.6 Getting to know your microscope Optical microscopes come in a variety of shapes EYEPIECE and sizes; however, all of them have the same OROCULARLENS basic parts.

What to do 1. Collect a microscope. Make sure you carry it with two hands, one around the arm and the other under the base; your teacher will MICROSCOPE COARSEFOCUS TUBE show you how. Place your microscope on KNOB the bench away from the edge.

2. Look closely at your microscope and use FINEFOCUS fi gure 1.11 to fi nd each of the labelled parts. KNOB OBJECTIVE LENS With a partner, try to decide what each part is used for. STAGE 3. If you can’t work out what some parts are for, write some questions about them as labels on the drawing. MIRROR 4. Join up with another pair to see whether they have the answers to any of your questions. BASE 5. Table 1.2 contains a description and a function for each part of the microscope but they are all Figure 1.11 mixed up. Unscramble the information and write the corrected table into your book. A standard light microscope. Microscopes that are used in schools may look a little 6. Compare your table with another group and different from those used in labratories, discuss any differences. but essentially they work the same way.

Table 1 . 2 Parts of a microscope Name of Description Function part eyepiece fl at bottom surface holds the slide in place, letting light (ocular) lens pass through it objective lens fl at surface to sit slides on, has hole adjusts the position of the lenses so in its centre, may have clips that the object can be seen clearly; can be coarse or fi ne focus knob iris-like aperture that can be light travels through it to the adjusted to allow light through eyepiece lens base knob that can be turned to move controls the amount of light passing the lenses through the object mirror the adjustable tube between the supports the microscope eyepiece and objective lenses stage lenses of different focal lengths that refl ects light up through the slide can be positioned above the slide into the lenses diaphragm round with a shiny surface used to get different magnifi cations microscope single lens closest to the eye bends the light to make the object tube look bigger

12 Science 8: A Contextual Approach

001_HQSP8_SI.indd1_HQSP8_SI.indd 1122 112/5/062/5/06 33:48:59:48:59 PMPM Using microscopes Microscopes are very expensive and delicate instruments. They should be used with care at all times. Here are the fi ve important rules to remember when using your microscope. • When carrying your microscope, always use both hands. • Keep your microscope well away from the edge of your workbench. • To prevent damage to your eyes, make sure that sunlight is not shining directly up the tube of your microscope. Use a lamp with a fi lter whenever possible. • Look from the side of the microscope and move the tube down so that it is as close to the microscope slide as possible. You can then focus your microscope by looking through the eyepiece or objective lens and moving the tube slowly upwards. • If your microscope lenses are dirty, use lens tissues to clean them. Never wipe them with paper towel or your fi ngers.

Microscopes and magnifi cation Optical microscope The magnifi cation of the microscope tells you how much bigger the image is than the real object. If the microscope has a magnifi cation of ×400, then the image you are looking at is 400 times bigger than Ocular lens Objective lens ×10 ×40 the actual object. (The symbol × stands for ‘magnifi ed by’.) To work out the magnifi cation, look at both the eyepiece lens

and the objective lens of the microscope. Each has a number on it, Magnifi cation working scientifically such as ×10 or ×20. Multiplying these numbers together gives you 10 × 40 = ×400 the total magnifi cation of the microscope. 01 Figure 1.12

Fields of view of the light microscope Calculating the total magnifi cation. How big is it really? When looking at specimens using a microscope, we have to remember how big they really are. First let’s look at a measurement chapter that makes sense to us—our height. We usually measure this in scciifiilele centimetres or metres. You may be 160 cm tall, or you may prefer to Cells vary in size from the say 1.60 m. If you had to measure the width of your foot, you would smallest bacterium (1 µm across) probably use centimetres or millimetres. For the width of a coin to nerve cells that can be over a you would probably use millimetres. The small objects that you see metre in length. Human skin cells under the microscope are usually measured in micrometres (µm). are about 50 µm across. A micrometre is one thousandth of a millimetre, or one millionth of a metre. How much do we see? When you look down your microscope you see only part of the specimen. The circle of light that you see is called the fi eld of view. The area covered by the fi eld of view varies between microscopes and according to the magnifi cation you are using. For example, if you use a magnifi cation of ×40, a typical microscope would have a fi eld of view around 4 mm in diameter. Table 1.3 lists the most common fi eld of view sizes. Note that as the magnifi cation increases the fi eld of view decreases.

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001_HQSP8_SI.indd1_HQSP8_SI.indd 1133 112/5/062/5/06 33:49:02:49:02 PMPM Table 1 . 3 Common magnifi cations and their fi elds of view Objective lens Ocular lens Total Field diameter Power magnification magnification magnification (mm) low (LP) 4 10 40 4.0 medium (MP) 10 10 100 1.6 high (HP) 40 10 400 0.4

   Imagine that a specimen observed at low power ,0 -0 (0 occupies about half of the fi eld of view. We know from table 1.3 that the fi eld of view has a diameter of 4 mm (4000 µm), therefore an object that occupies half of the fi eld of view would be about 2000 µm long.

MM MM —M

Figure 1.13 The fi eld of view gets smaller as the magnifi cation gets higher.

SCIENCE work Using a microscope EXPERIMENT 1.7 Aim To become familiar with the use of a microscope. Materials • light microscope • tissue • mini grid (optional) • microscope lamp with fi lter • newspaper • slides and cover slips • tweezers • cotton wool • hair • clear plastic ruler • fabric

Part A: How big is it really?

Method 1. Collect a microscope and carry it with both hands to the workbench, placing it well away from the edge. 2. Work out the magnifi cation of your microscope when using the low and high power lenses. 3. Adjust your mirror so that an appropriate amount of light passes through the hole in the stage. 4. Place a clear plastic ruler on the stage of your microscope so that you can focus on the millimetre scale. Once you have focused your microscope, the area that you can see is called the ‘fi eld of view’. It should appear as a round circle of light. 5. Using your low power objective lens, measure the width of your fi eld of view. Note this down in your book. 6. Using your high power objective lens, measure the width of your fi eld of view. Note this down in your book. How does it compare with your fi eld of view using the low power objective lens?

14 Science 8: A Contextual Approach

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Extension Your teacher may have a ‘mini grid’ that you can use to estimate the size of what you see under the microscope. Learn how to use the mini grid and then estimate the width of a strand of your hair. If you don’t have a mini grid, remember the width of your fi eld of view measured above and use this to estimate the width of the hair. Compare your hair with other people’s hair—is it thicker or thinner? Is blond, red or dark hair thinnest? Compare curly and straight hair—is there a difference in the thickness?

Part B: Upside down and back-to-front

Method 1. Cut out a piece of newsprint 1 cm square. Make certain that it contains the letter ‘e’. 2. Place the print onto a microscope slide. Place a cover slip over the top of this. 3. Use the low power objective lens. While watching from the side, use the coarse adjustment to lower the objective lens until it is just above the stage. Pressing it down too far may shatter the slide. 4. While looking through the eyepiece, carefully turn the coarse adjustment until the specimen can be seen clearly. 5. Carefully use the fi ne adjustment so that you can see the details of your specimen as clearly as possible. 6. Carefully move the slide until you have an ‘e’ in focus. 7. Pencil a sketch of what you see. Is it right side up, upside down or back-to-front? How much of the fi eld of view is covered by the ‘e’ at this magnifi cation?

8. In which direction did the paper under the microscope move when you moved the slide to working scientifically the left? What about when you moved it towards you? 9. Record the magnifi cation that you are using. 01

Evaluation What diffi culties did you encounter while using the microscope? How could you improve your microscope technique?

Extension chapter Look at some other specimens, such as tissue, cotton wool, coloured paper and frayed edges of fabric. Sketch what you see and label the diagrams clearly. Remember to write down the magnifi cation that you are using.

Figure 1.14 A microscope from 1716 sccii iilele —an expensive toy for the f inquisitive rich. During the seventeenth and eighteenth centuries people could not think of any ways that microscopes could be useful. They regarded them as just a toy. They would be amazed to know that of all the tools used by scientists today, the microscope is among the most useful. Microscopes allow scientists to ‘look into’ living things in a very detailed way.

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001_HQSP8_SI.indd1_HQSP8_SI.indd 1155 112/5/062/5/06 33:49:05:49:05 PMPM Electron microscopes Electron microscopes use beams of tiny particles called electrons scciifiilele rather than a light source, and can magnify up to a million times! All images are seen in black and white. They cannot be used for The fi rst electron microscope viewing live specimens. was built by the German physicist Ernst Ruska. Electron The fi rst type of electron microscope to be developed was the microscopes are more powerful transmission electron microscope (TEM). The TEM sends a beam of than optical microscopes electrons through an ultra-thin section of a specimen that has been because magnifi cation is stained with an electron-dense stain such as lead or uranium. The increased with shorter beam of electrons is affected by the structure of the specimen and a wavelengths and electron waves are much shorter than ordinary picture is created. light waves. The scanning electron microscope (SEM) was developed later and it has many uses. A simplifi ed version of how an SEM works is shown in fi gure 1.16.

Figure 1.15 An electron microscope enables us to see things like this fl ea in amazing detail.

electron source

electromagnets narrow the image on screen electron beam

detector

emitted electrons

Figure 1.16 specimen A simplifi ed explanation of how we covered with stage electron-dense see things with a scanning electron material microscope.

16 Science 8: A Contextual Approach

001_HQSP8_SI.indd1_HQSP8_SI.indd 1166 112/5/062/5/06 33:49:08:49:08 PMPM questions 1.3

1. Name the two main types of microscope (b) How many micrometres are there in one and list the main similarities and differences millimetre? If a cell is 50 µm in diameter, between them. how big is it in millimetres? Would 2. If you wanted a very detailed image of a cell, we be able to see this cell without a which microscope would you use? microscope? 3. List the ways that an image seen under a 7. What is the greatest magnifi cation you can light microscope can differ from the original gain with the microscope you used in your specimen placed on the stage. laboratory? Explain how you calculated your 4. Outline the steps you would follow to obtain answer. a clear focus using a light microscope on 8. Create a rhyme that would help you low power and then on high power. remember how to use a microscope. 5. Explain why it is important for a specimen 9. Design a poster for use in the classroom viewed using a light microscope to be very demonstrating for students the correct thin. way to: 6. (a) If our eyes can see things as small as (a) carry and set up a microscope. 0.1 mm, and one cell is one-tenth of (b) focus the microscope on low, medium this size, what is the size of the cell in and high power. micrometres?

11.4.4 Let's experiment

Interactive scciifiilele Fair tests A variable is a factor that can When you plan an experiment, you should be sure that it is a fair change the outcome of an test. A fair test changes only one variable at a time and repeats each experiment, e.g. temperature, test at least three times to reduce errors. Other people should be amount of light, brand of tyre. able to carry out the same experiment and get similar results.

FAIR TEST

Title Aim Hypothesis Variables Method Results Evaluation Decide on Write your Make a List all the things How will you How will you How good is your a name for question. prediction. that can change. carry out the record your method? Can your test. experiment? results? you improve the accuracy of your results?

CONTROL All variables should be kept the same, except the one being tested. Figure 1.20 There are many steps to follow when planning a fair test.

18 Science 8: A Contextual Approach

001_HQSP8_SI.indd1_HQSP8_SI.indd 1188 112/5/062/5/06 33:49:20:49:20 PMPM Chapter review

0aim 1 Bunsen burner keyeye ideasi conclusion control True or False? Which of the statements below are true? If you think any are data false, rewrite them as correct statements. equipment experiment 1. The science laboratory has rules that need to be followed for your own and evaluation other people’s safety. fair test Scientifi c drawings are done in colour. hypothesis 2. inference 3. When using a Bunsen burner, the blue fl ame is the safety fl ame and the yellow

KEY TERMS KEY investigation fl ame is used for heating. laboratory 4. An observation is an educated guess. mass measurement 5. Graphs allow trends and patterns to be observed easily. meniscus 6. Weight and mass are the same thing. method 7. Distance is measured in grams. observations results 8. Inferences are suggested explanations for our observations. safety 9. A science laboratory is any place where experiments and investigations are scientist carried out. temperature A light microscope gives a greater magnifi cation than an electron microscope. title 10. variable volume weight review questions

1. Explain why a hypothesis is sometimes 5. A microscope has a ×5 eyepiece and three described as being an ‘educated guess’. objective lenses: ×4, ×10 and ×40. Draw up a 2. List possible points to include when writing a table that shows the magnifications that could practical report. be achieved using this microscope and how each magnification could be produced. 3. Imagine that you need to describe a Bunsen burner to someone who hasn’t seen one before. 6. What is the difference between an observation Explain, without using a diagram, what the and an inference? Make up your own table of parts of a Bunsen burner look like, how they fi t three matching observations and inferences. together, and how they work. 4. Unscramble the names of laboratory equipment in the following table, then match each item with its correct use. Equipment Used to snuben errbun hold test-tubes while heating zuega tam spread heat when heating a fl ask or a beaker gnots heat things smearguni inderlcy pick up small amounts of solids poringateva hids accurately measure the volume of a liquid laptusa evaporate a small amount of solution

34 Science 8: A Contextual Approach

001_HQSP8_SI.indd1_HQSP8_SI.indd 3344 112/5/062/5/06 33:52:54:52:54 PMPM 7. For each of the following statements correct the Some suggestions are: Alfred Nobel, Marie units used so that the sentence makes sense. Curie, Sir Frank Macfarlane Burnet, Albert (a) A baby weighs 3975 cm. Einstein, Suzanne Cory, Don Metcalfe, Peter (b) I drank 1.0 m of water. Doherty, Isaac Newton, Gustav Nossal, Barry (c) In 1 hour, Friedrich ran 4 kg. Marshall, Robin Warren. (d) Mary has a height of 163 s. 12. A trip to the supermarket will never be the same. Murray Laidlaw of the UK has been awarded a 8. Why should you never shake a test-tube with $75 000 grant to build a better shopping trolley. your thumb over the top of it? His hi-tech plans include a sophisticated Global 9. Design a cartoon illustrating one dangerous Positioning System (GPS) so shoppers don’t situation in your science laboratory. get lost, a touch screen display where previous 10. The following is a list of ways to reduce the risk shopping lists can be stored, and an in-built of fi re: price scanner to minimise check-out delays. (a) Clear away fallen leaves, long grass and The trolley will even ask shoppers if they’ve dead undergrowth from within 30 m of forgotten any important ingredients! your home. Design and draw or build a model of your (b) Remove wood piles, heavy mulch and other own Robotrolley. fl ammable materials. (c) Check that hoses reach all sides of the house. (d) Check that electrical leads are not worn or frayed. Explain how each of these preventative measures reduces the risk of fi re. 11. Create a booklet that tells the story of a famous scientist. The booklet is to be used by primary schools for their Year 4 level and should include the birthplace of the person, what the person is famous for, and in what ways they have contributed to our scientifi c knowledge. Make sure it is interesting, well illustrated and suitable for Year 4 students. Figure 1.35 Robotrolley.

reflection science complete In this chapter you have learnt many new skills and discovered how we use science every day at home, at school and at work. Now is the time to complete the third and fourth columns in your KWLH chart. Your teacher may want to see a copy of your chart. Present your laboratory safety policy to your School Council. Make sure that you have fi rst trialled your report with another group of students or teachers. You should ask the trial audience for feedback on how you can

improve your report. 1. T 2. F 3. F 4. F 5. T 6. F 7. F 8. T 9. T 10. F F 10. T 9. T 8. F 7. F 6. T 5. F 4. F 3. F 2. T 1. 35

001_HQSP8_SI.indd1_HQSP8_SI.indd 3355 112/5/062/5/06 33:52:56:52:56 PMPM