Teaching Symmetry in the Elementary Curriculum
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Molecular Symmetry
Molecular Symmetry Symmetry helps us understand molecular structure, some chemical properties, and characteristics of physical properties (spectroscopy) – used with group theory to predict vibrational spectra for the identification of molecular shape, and as a tool for understanding electronic structure and bonding. Symmetrical : implies the species possesses a number of indistinguishable configurations. 1 Group Theory : mathematical treatment of symmetry. symmetry operation – an operation performed on an object which leaves it in a configuration that is indistinguishable from, and superimposable on, the original configuration. symmetry elements – the points, lines, or planes to which a symmetry operation is carried out. Element Operation Symbol Identity Identity E Symmetry plane Reflection in the plane σ Inversion center Inversion of a point x,y,z to -x,-y,-z i Proper axis Rotation by (360/n)° Cn 1. Rotation by (360/n)° Improper axis S 2. Reflection in plane perpendicular to rotation axis n Proper axes of rotation (C n) Rotation with respect to a line (axis of rotation). •Cn is a rotation of (360/n)°. •C2 = 180° rotation, C 3 = 120° rotation, C 4 = 90° rotation, C 5 = 72° rotation, C 6 = 60° rotation… •Each rotation brings you to an indistinguishable state from the original. However, rotation by 90° about the same axis does not give back the identical molecule. XeF 4 is square planar. Therefore H 2O does NOT possess It has four different C 2 axes. a C 4 symmetry axis. A C 4 axis out of the page is called the principle axis because it has the largest n . By convention, the principle axis is in the z-direction 2 3 Reflection through a planes of symmetry (mirror plane) If reflection of all parts of a molecule through a plane produced an indistinguishable configuration, the symmetry element is called a mirror plane or plane of symmetry . -
History of Mathematics
Georgia Department of Education History of Mathematics K-12 Mathematics Introduction The Georgia Mathematics Curriculum focuses on actively engaging the students in the development of mathematical understanding by using manipulatives and a variety of representations, working independently and cooperatively to solve problems, estimating and computing efficiently, and conducting investigations and recording findings. There is a shift towards applying mathematical concepts and skills in the context of authentic problems and for the student to understand concepts rather than merely follow a sequence of procedures. In mathematics classrooms, students will learn to think critically in a mathematical way with an understanding that there are many different ways to a solution and sometimes more than one right answer in applied mathematics. Mathematics is the economy of information. The central idea of all mathematics is to discover how knowing some things well, via reasoning, permit students to know much else—without having to commit the information to memory as a separate fact. It is the reasoned, logical connections that make mathematics coherent. The implementation of the Georgia Standards of Excellence in Mathematics places a greater emphasis on sense making, problem solving, reasoning, representation, connections, and communication. History of Mathematics History of Mathematics is a one-semester elective course option for students who have completed AP Calculus or are taking AP Calculus concurrently. It traces the development of major branches of mathematics throughout history, specifically algebra, geometry, number theory, and methods of proofs, how that development was influenced by the needs of various cultures, and how the mathematics in turn influenced culture. The course extends the numbers and counting, algebra, geometry, and data analysis and probability strands from previous courses, and includes a new history strand. -
The Age of Addiction David T. Courtwright Belknap (2019) Opioids
The Age of Addiction David T. Courtwright Belknap (2019) Opioids, processed foods, social-media apps: we navigate an addictive environment rife with products that target neural pathways involved in emotion and appetite. In this incisive medical history, David Courtwright traces the evolution of “limbic capitalism” from prehistory. Meshing psychology, culture, socio-economics and urbanization, it’s a story deeply entangled in slavery, corruption and profiteering. Although reform has proved complex, Courtwright posits a solution: an alliance of progressives and traditionalists aimed at combating excess through policy, taxation and public education. Cosmological Koans Anthony Aguirre W. W. Norton (2019) Cosmologist Anthony Aguirre explores the nature of the physical Universe through an intriguing medium — the koan, that paradoxical riddle of Zen Buddhist teaching. Aguirre uses the approach playfully, to explore the “strange hinterland” between the realities of cosmic structure and our individual perception of them. But whereas his discussions of time, space, motion, forces and the quantum are eloquent, the addition of a second framing device — a fictional journey from Enlightenment Italy to China — often obscures rather than clarifies these chewy cosmological concepts and theories. Vanishing Fish Daniel Pauly Greystone (2019) In 1995, marine biologist Daniel Pauly coined the term ‘shifting baselines’ to describe perceptions of environmental degradation: what is viewed as pristine today would strike our ancestors as damaged. In these trenchant essays, Pauly trains that lens on fisheries, revealing a global ‘aquacalypse’. A “toxic triad” of under-reported catches, overfishing and deflected blame drives the crisis, he argues, complicated by issues such as the fishmeal industry, which absorbs a quarter of the global catch. -
Chapter 1 – Symmetry of Molecules – P. 1
Chapter 1 – Symmetry of Molecules – p. 1 - 1. Symmetry of Molecules 1.1 Symmetry Elements · Symmetry operation: Operation that transforms a molecule to an equivalent position and orientation, i.e. after the operation every point of the molecule is coincident with an equivalent point. · Symmetry element: Geometrical entity (line, plane or point) which respect to which one or more symmetry operations can be carried out. In molecules there are only four types of symmetry elements or operations: · Mirror planes: reflection with respect to plane; notation: s · Center of inversion: inversion of all atom positions with respect to inversion center, notation i · Proper axis: Rotation by 2p/n with respect to the axis, notation Cn · Improper axis: Rotation by 2p/n with respect to the axis, followed by reflection with respect to plane, perpendicular to axis, notation Sn Formally, this classification can be further simplified by expressing the inversion i as an improper rotation S2 and the reflection s as an improper rotation S1. Thus, the only symmetry elements in molecules are Cn and Sn. Important: Successive execution of two symmetry operation corresponds to another symmetry operation of the molecule. In order to make this statement a general rule, we require one more symmetry operation, the identity E. (1.1: Symmetry elements in CH4, successive execution of symmetry operations) 1.2. Systematic classification by symmetry groups According to their inherent symmetry elements, molecules can be classified systematically in so called symmetry groups. We use the so-called Schönfliess notation to name the groups, Chapter 1 – Symmetry of Molecules – p. 2 - which is the usual notation for molecules. -
Music: Broken Symmetry, Geometry, and Complexity Gary W
Music: Broken Symmetry, Geometry, and Complexity Gary W. Don, Karyn K. Muir, Gordon B. Volk, James S. Walker he relation between mathematics and Melody contains both pitch and rhythm. Is • music has a long and rich history, in- it possible to objectively describe their con- cluding: Pythagorean harmonic theory, nection? fundamentals and overtones, frequency Is it possible to objectively describe the com- • Tand pitch, and mathematical group the- plexity of musical rhythm? ory in musical scores [7, 47, 56, 15]. This article In discussing these and other questions, we shall is part of a special issue on the theme of math- outline the mathematical methods we use and ematics, creativity, and the arts. We shall explore provide some illustrative examples from a wide some of the ways that mathematics can aid in variety of music. creativity and understanding artistic expression The paper is organized as follows. We first sum- in the realm of the musical arts. In particular, we marize the mathematical method of Gabor trans- hope to provide some intriguing new insights on forms (also known as short-time Fourier trans- such questions as: forms, or spectrograms). This summary empha- sizes the use of a discrete Gabor frame to perform Does Louis Armstrong’s voice sound like his • the analysis. The section that follows illustrates trumpet? the value of spectrograms in providing objec- What do Ludwig van Beethoven, Ben- • tive descriptions of musical performance and the ny Goodman, and Jimi Hendrix have in geometric time-frequency structure of recorded common? musical sound. Our examples cover a wide range How does the brain fool us sometimes • of musical genres and interpretation styles, in- when listening to music? And how have cluding: Pavarotti singing an aria by Puccini [17], composers used such illusions? the 1982 Atlanta Symphony Orchestra recording How can mathematics help us create new of Copland’s Appalachian Spring symphony [5], • music? the 1950 Louis Armstrong recording of “La Vie en Rose” [64], the 1970 rock music introduction to Gary W. -
20. Geometry of the Circle (SC)
20. GEOMETRY OF THE CIRCLE PARTS OF THE CIRCLE Segments When we speak of a circle we may be referring to the plane figure itself or the boundary of the shape, called the circumference. In solving problems involving the circle, we must be familiar with several theorems. In order to understand these theorems, we review the names given to parts of a circle. Diameter and chord The region that is encompassed between an arc and a chord is called a segment. The region between the chord and the minor arc is called the minor segment. The region between the chord and the major arc is called the major segment. If the chord is a diameter, then both segments are equal and are called semi-circles. The straight line joining any two points on the circle is called a chord. Sectors A diameter is a chord that passes through the center of the circle. It is, therefore, the longest possible chord of a circle. In the diagram, O is the center of the circle, AB is a diameter and PQ is also a chord. Arcs The region that is enclosed by any two radii and an arc is called a sector. If the region is bounded by the two radii and a minor arc, then it is called the minor sector. www.faspassmaths.comIf the region is bounded by two radii and the major arc, it is called the major sector. An arc of a circle is the part of the circumference of the circle that is cut off by a chord. -
Symmetry of Graphs. Circles
Symmetry of graphs. Circles Symmetry of graphs. Circles 1 / 10 Today we will be interested in reflection across the x-axis, reflection across the y-axis and reflection across the origin. Reflection across y reflection across x reflection across (0; 0) Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. It is called symmetric if some geometric move preserves it Symmetry of graphs. Circles 2 / 10 Reflection across y reflection across x reflection across (0; 0) Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. It is called symmetric if some geometric move preserves it Today we will be interested in reflection across the x-axis, reflection across the y-axis and reflection across the origin. Symmetry of graphs. Circles 2 / 10 Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. It is called symmetric if some geometric move preserves it Today we will be interested in reflection across the x-axis, reflection across the y-axis and reflection across the origin. Reflection across y reflection across x reflection across (0; 0) Symmetry of graphs. Circles 2 / 10 Sends (x,y) to (-x,y) Sends (x,y) to (x,-y) Sends (x,y) to (-x,-y) Examples with Symmetry What is Symmetry? Take some geometrical object. -
Decagonal and Quasi-Crystalline Tilings in Medieval Islamic Architecture
REPORTS 21. Materials and methods are available as supporting 27. N. Panagia et al., Astrophys. J. 459, L17 (1996). Supporting Online Material material on Science Online. 28. The authors would like to thank L. Nelson for providing www.sciencemag.org/cgi/content/full/315/5815/1103/DC1 22. A. Heger, N. Langer, Astron. Astrophys. 334, 210 (1998). access to the Bishop/Sherbrooke Beowulf cluster (Elix3) Materials and Methods 23. A. P. Crotts, S. R. Heathcote, Nature 350, 683 (1991). which was used to perform the interacting winds SOM Text 24. J. Xu, A. Crotts, W. Kunkel, Astrophys. J. 451, 806 (1995). calculations. The binary merger calculations were Tables S1 and S2 25. B. Sugerman, A. Crotts, W. Kunkel, S. Heathcote, performed on the UK Astrophysical Fluids Facility. References S. Lawrence, Astrophys. J. 627, 888 (2005). T.M. acknowledges support from the Research Training Movies S1 and S2 26. N. Soker, Astrophys. J., in press; preprint available online Network “Gamma-Ray Bursts: An Enigma and a Tool” 16 October 2006; accepted 15 January 2007 (http://xxx.lanl.gov/abs/astro-ph/0610655) during part of this work. 10.1126/science.1136351 be drawn using the direct strapwork method Decagonal and Quasi-Crystalline (Fig. 1, A to D). However, an alternative geometric construction can generate the same pattern (Fig. 1E, right). At the intersections Tilings in Medieval Islamic Architecture between all pairs of line segments not within a 10/3 star, bisecting the larger 108° angle yields 1 2 Peter J. Lu * and Paul J. Steinhardt line segments (dotted red in the figure) that, when extended until they intersect, form three distinct The conventional view holds that girih (geometric star-and-polygon, or strapwork) patterns in polygons: the decagon decorated with a 10/3 star medieval Islamic architecture were conceived by their designers as a network of zigzagging lines, line pattern, an elongated hexagon decorated where the lines were drafted directly with a straightedge and a compass. -
SOME GEOMETRY in HIGH-DIMENSIONAL SPACES 11 Containing Cn(S) Tends to ∞ with N
SOME GEOMETRY IN HIGH-DIMENSIONAL SPACES MATH 527A 1. Introduction Our geometric intuition is derived from three-dimensional space. Three coordinates suffice. Many objects of interest in analysis, however, require far more coordinates for a complete description. For example, a function f with domain [−1; 1] is defined by infinitely many \coordi- nates" f(t), one for each t 2 [−1; 1]. Or, we could consider f as being P1 n determined by its Taylor series n=0 ant (when such a representation exists). In that case, the numbers a0; a1; a2;::: could be thought of as coordinates. Perhaps the association of Fourier coefficients (there are countably many of them) to a periodic function is familiar; those are again coordinates of a sort. Strange Things can happen in infinite dimensions. One usually meets these, gradually (reluctantly?), in a course on Real Analysis or Func- tional Analysis. But infinite dimensional spaces need not always be completely mysterious; sometimes one lucks out and can watch a \coun- terintuitive" phenomenon developing in Rn for large n. This might be of use in one of several ways: perhaps the behavior for large but finite n is already useful, or one can deduce an interesting statement about limn!1 of something, or a peculiarity of infinite-dimensional spaces is illuminated. I will describe some curious features of cubes and balls in Rn, as n ! 1. These illustrate a phenomenon called concentration of measure. It will turn out that the important law of large numbers from probability theory is just one manifestation of high-dimensional geometry. -
Geometry Topics
GEOMETRY TOPICS Transformations Rotation Turn! Reflection Flip! Translation Slide! After any of these transformations (turn, flip or slide), the shape still has the same size so the shapes are congruent. Rotations Rotation means turning around a center. The distance from the center to any point on the shape stays the same. The rotation has the same size as the original shape. Here a triangle is rotated around the point marked with a "+" Translations In Geometry, "Translation" simply means Moving. The translation has the same size of the original shape. To Translate a shape: Every point of the shape must move: the same distance in the same direction. Reflections A reflection is a flip over a line. In a Reflection every point is the same distance from a central line. The reflection has the same size as the original image. The central line is called the Mirror Line ... Mirror Lines can be in any direction. Reflection Symmetry Reflection Symmetry (sometimes called Line Symmetry or Mirror Symmetry) is easy to see, because one half is the reflection of the other half. Here my dog "Flame" has her face made perfectly symmetrical with a bit of photo magic. The white line down the center is the Line of Symmetry (also called the "Mirror Line") The reflection in this lake also has symmetry, but in this case: -The Line of Symmetry runs left-to-right (horizontally) -It is not perfect symmetry, because of the lake surface. Line of Symmetry The Line of Symmetry (also called the Mirror Line) can be in any direction. But there are four common directions, and they are named for the line they make on the standard XY graph. -
A CONCISE MINI HISTORY of GEOMETRY 1. Origin And
Kragujevac Journal of Mathematics Volume 38(1) (2014), Pages 5{21. A CONCISE MINI HISTORY OF GEOMETRY LEOPOLD VERSTRAELEN 1. Origin and development in Old Greece Mathematics was the crowning and lasting achievement of the ancient Greek cul- ture. To more or less extent, arithmetical and geometrical problems had been ex- plored already before, in several previous civilisations at various parts of the world, within a kind of practical mathematical scientific context. The knowledge which in particular as such first had been acquired in Mesopotamia and later on in Egypt, and the philosophical reflections on its meaning and its nature by \the Old Greeks", resulted in the sublime creation of mathematics as a characteristically abstract and deductive science. The name for this science, \mathematics", stems from the Greek language, and basically means \knowledge and understanding", and became of use in most other languages as well; realising however that, as a matter of fact, it is really an art to reach new knowledge and better understanding, the Dutch term for mathematics, \wiskunde", in translation: \the art to achieve wisdom", might be even more appropriate. For specimens of the human kind, \nature" essentially stands for their organised thoughts about sensations and perceptions of \their worlds outside and inside" and \doing mathematics" basically stands for their thoughtful living in \the universe" of their idealisations and abstractions of these sensations and perceptions. Or, as Stewart stated in the revised book \What is Mathematics?" of Courant and Robbins: \Mathematics links the abstract world of mental concepts to the real world of physical things without being located completely in either". -
Books in Brief Hypothesis Might Be That a New Drug Has No Effect
BOOKS & ARTS COMMENT includes not just one correct answer, but all other possibilities. In a medical experiment, the null Books in brief hypothesis might be that a new drug has no effect. But the hypothesis will come pack- The Age of Addiction aged in a statistical model that assumes that David T. Courtwright BELKNAP (2019) there is zero systematic error. This is not Opioids, processed foods, social-media apps: we navigate an necessarily true: errors can arise even in a addictive environment rife with products that target neural pathways randomized, blinded study, for example if involved in emotion and appetite. In this incisive medical history, some participants work out which treatment David Courtwright traces the evolution of “limbic capitalism” from group they have been assigned to. This can prehistory. Meshing psychology, culture, socio-economics and lead to rejection of the null hypothesis even urbanization, it’s a story deeply entangled in slavery, corruption when the new drug has no effect — as can and profiteering. Although reform has proved complex, Courtwright other complexities, such as unmodelled posits a solution: an alliance of progressives and traditionalists aimed measurement error. at combating excess through policy, taxation and public education. To say that P = 0.05 should lead to acceptance of the alternative hypothesis is tempting — a few million scientists do it Cosmological Koans every year. But it is wrong, and has led to Anthony Aguirre W. W. NORTON (2019) replication crises in many areas of the social, Cosmologist Anthony Aguirre explores the nature of the physical behavioural and biological sciences. Universe through an intriguing medium — the koan, that paradoxical Statistics — to paraphrase Homer riddle of Zen Buddhist teaching.