 Topology (Geometry and the Imagination)  Conway, Doyle, Gilman, Thurston; The Geometry Center
Topology is the theory of shapes that are allowed to stretch, compress, flex and bend, but without tearing or gluing. For example, a square is topologically equivalent to a circle, since a square can be continously deformed into a circle. As another example,
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 Topology (Graphics Archive, Special Topics)  The Geometry Center
Properties of objects that don't change when they are stretched or twisted (Klein bottle, Moebius band).
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 TopSecretMath.org  Donald Endriss
Stepbystep JavaScript tutorials for learning how to factor several different kinds of trinomials using the CAB method.
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 Tostaky.Biz  Jerome Verstrynge
JavaScript utilities formatted for the smaller screens of tablets and smartphones: timer, stopwatch, world clocks, and other timekeeping tools; and unit converters for area, force, length, torque, weight, and more.
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 Totally Free Math  Terry Wesner
A free downloadable 3rd edition elementary algebra textbook with accompanying ancillaries and no advertising.
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 Totally Tessellated  Bhushan, Kay, & Williams
A comprehensive introduction to tessellations and tilings  the basic underlying mathematics and examples of tessellations in real life. The highly illustrated, printerfriendly site includes history (tessellations in mathematics and science, decorative
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 To teach definitions in geometry or teach to define?  Michael de Villiers; Mathematics Education, Univ. of DurbanWestville, South Africa
This paper argues from a theoretical standpoint that students should be actively
engaged in the defining of geometric concepts like the quadrilaterals, and
presents some data relating to a teaching experiment aimed at developing
students' ability to
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 TotiPM  Jordi Lagares Roset, Prof. of Mathematics, Girona
Una página basicamente en Catalán, pero con referencias también en castellano e inglés. Páginas didácticas, problemas, software. A page primarily in Catalan but with Spanish and English language references. Lessons,
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Tour: M.C. Escher  Life and Work  National Gallery of Art, Washington, DC
A tour of four virtual rooms devoted to the art of M. C. Escher. For each graphic a larger picture with accompanying commentary is available by clicking on a small picture. The gallery has more than 400 works by Escher with many images available online.
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 Tournament of Towns  Math Net, University of Toronto
A worldwide problem solving competition in mathematics. The contest attracts students of all mathematical interests and abilities with its inclusive rules and creative problems  some as challenging as those of the International Mathematical Olympiad.
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 Tournament Scheduling  Math Forum, Ask Dr. Math Common Question
A selection of answers to questions about scheduling tournaments, from "Can you help me construct a schedule for a round robin style junior hockey tournament with two divisions using only four fields?" to "What are the odds of one person predicting the
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 A Tour of Fractions  Math Forum
The Web often seems more like a maze than an organized set of resources. To help you find what you need, the Math Forum presents a 'tour' of fractions, offering links to lessons, activities, and materials, questions and answers from Ask Dr. Math, and
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 Toward a Fairer Expansion Draft  Ivars Peterson (MathLand)
When new teams are brought into an established league, the team owners usually take turns picking players from a pool of available talent. The conventional method for such drafts, however, often produces unfair results. For example, if one of two owners
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 The Tower of Hanoi  Andrew Cumming
Interactive version of the famous logic puzzle, in html and VRML versions, with a separate page about solving it.
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 Tower of Hanoi  Math Forum, a Classic Problem from the Ask Dr. Math FAQ
There are three posts. Disks of different sizes are placed on the lefthand post, arranged by size with the smallest on top. You are to transfer all the disks to the righthand post in the fewest possible moves, without ever placing a larger disk on a smaller
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 Tower of Hanoi on the Web  Miroslav Kolar
The legend: A group of Eastern monks are the keepers of three towers on which sit 64 golden rings. Originally all 64 rings were stacked on one tower with each ring smaller than the one beneath. The monks are to move the rings from this first tower to
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 Tower of Hanoi (SMILE)  Paul Eubanks, Washington High School
A lesson for grades 612 designed to teach students to discover a pattern and to evaluate an exponential expression. From the Patterns and Logic section of a collection of almost 200 single concept lessons by the Science and Mathematics Initiative for
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 Toying with Reality: Java Applets and VRML  Paul Flavin
Virtual Reality: Modeling with Math, and a little Java. Applets to manipulate: The Pythagorean Theorem; Equation Grapher: "You type, I Graph"; Graphing Vector Calculator; Java 3d Visualizer; Virtual Rubik's Cube; Raytracing applet; Java Calculator; Play
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 Trachtenberg Speed Math  Alpha Centauri Software
Software that teaches Jakow Trachtenberg's speed system of basic mathematics that he invented while imprisoned by Hitler during WWII. For Windows only. Demo version available.
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 Trachtenberg Speed System  Math Forum, Ask Dr. Math FAQ
An introduction to Trachtenberg's system of performing highspeed multiplication, division, addition, subtraction, and square root, all in one's head, with references.
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 Tracking  Education Week on the Web
Should schools  as the engine of democracy  provide relatively similar curricula for all students? Or should they instead sort students by skill levels and prepare them for their different roles as adults? A discussion of the pros and cons of tracking,
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 Tractrix Java Applet Class  PHD Computer Consultants Ltd
Download Tractrix.zip, a Java applet that makes the kind of pretty swirling patterns which Dutch mathematician Huygens originally named in 1692. Specify applet width and height, background and foreground color, coordinate pairs that will identify corners,
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 Traditional Schooling: Articles and Research  Carolyn K., Hoagies' Gifted Education Page
Articles and reports on traditional schooling issues: Academic Acceleration; Advocacy; Bullies; Curriculum Adjustments; Early (or late) Kindergarten; Educational Theories; Grouping; Individualized Education Profiles (IEPs); Mentors; Success Stories; Testing
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 Traffic Jam  Math Forum
Equal numbers of people face each other with one open slot between them. Everybody faces the open slot. If there are 6 people there will be 7 slots, 6 of
which must always have people in them. People must attempt to exchange places without turning around.
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 Traffic Signs  Richard C. Moeur
Graphics of the most commonly used traffic signs in the United States, useful for challenging students to find symmetrical signs (in addition to polygons).
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 Transformational Geometry  Leslie Howe
Java applets to illustrate translation, rotation, glide reflection, etc. Directions for tessellations by hand and using dot paper. Links to sites of artists that illustrate these ideas.
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 Transformations and Tessellations  Lynda Kozicz Leahey
A unit introducing the concepts of transformations and tessellations. Students will explore the attributes of transformations: reflections, translations, rotations and dilations by using pattern blocks, algebraic notation and computer design. They will
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 Transformations  David A. Reid
A transformation is a onetoone mapping on a set of points. The most common transformations map the points of the plane onto themselves, in a way which keeps all lengths the same. These transformations are called isometries. Another common sort of transformation
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 Transformulas  Jedidiah Butler
Blog about transformational geometry, subtitled "picture = 100 formulas." Posts, which feature Butler's original GeoGebra applets and teaching notes, date back to March, 2014: "One Formula ... to Rule them All," "Circles Part 2: Angle Relationships,"
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 Transmath  A CBL Mathematics Tutor  Joanna Brown
Transmath is a computerbased (Windows platform) mathematics tutor designed to strengthen and consolidate the basic mathematical knowledge of students commencing numerate degrees. Module exercises, featuring animations, come with constructive interactive
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 Transversal of a Latin Square  Jay's Corner
A transversal in a Latin Square is a collection of positions, one from each row and one from each column, so that the colors that are in these positions are all different. This page shows an example of a transversal in a 4x4 Latin square
See also Transversals
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 The Travelling Monkey  Ivars Peterson (MathLand)
One of the classic problems of planning ahead concerns a traveling salesman who must visit customers in a number of cities scattered across the country and then return home. The problem is to find the shortest possible route visiting each city only once.
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 The Travelling Salesman's Problem  Manu Konchady
A trucking or delivery company is focused on optimum delivery cost. This can be achieved by using a system which determines the best highway route for each load. An optimum highway route can be displayed on a map. A route with 16 nodes is used to test
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 Travel Triangles (SMILE)  Sarah Barrett, Mars Hill School
A middle and high school geometry lesson designed to teach students to review and demonstrate an understanding of the three kinds of angles (by degrees). From the Geometry and Measurement section of a collection of almost 200 single concept lessons by
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 The Treb Challenge  GlobalSpec, Inc.
Custom build a trebuchet for three challenges: distance, accuracy, and power. Between launches, continue modifying the catapultlike seige engine's projectile weight, launch angle, gravity, wind, counterweight mass and height. After each challenge, the
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 TreeAge Software, Inc.
Producer of decision analysis software. Product information, interactive demos and trial download, FAQ and technical support, ordering, and registration.
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 TREEFROG Mathematical Software  John Moores University, Liverpool, UK
Modular software for Windows, intended to be used along with traditional teaching methods, to provide instant feedback at each stage. It covers basic order of operations; manipulation of fractions; transposition of formulae and the quadratic equation;
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 TREEFROG selfassessment system  Strickland, AlJumeili
An MSDOS and Windows program for checking math skills, based on mathematical rules. A student is presented with an expression (say integral of x cos x d x, or x2+3x+2 = 0) and told to convert it to another equivalent form (function of x + constant, x
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 TrianCal  Jesús Sánchez
This free dynamic calculator accepts any combination of triangle sidelengths, heights, angles, areas, or perimeters. It then solves for the remaining values and measures, further offering a GeoGebra sketch. Watch TrianCal in action, with subtitles in
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 Triangle Calculator  Peter Chrenko
Select SideSideSide (SSS), SideAngleSide (SAS), AngleSideAngle (ASA), or SideSideAngle (SSA) congruence, then enter three known sidelengths or angles, and this JavaScript returns the triangle's remaining measurements. This calculator also uniquely
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 Triangle Centers  Clark Kimberling; Dept. of Mathematics, Univ. of Evansville, Evansville, IN
A listing, with description and illustration, of 20thcentury triangle centers (including: Schiffler Point, Exeter Point, Parry Point, congruent isoscelizers point, Yff Center of Congruence, isoperimetric point and equal detour point, AjimaMalfatti Points,
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 Triangle Congruence  Math Forum, Ask Dr. Math Common Question
A selection of answers to questions about triangle congruences, such as "Why can't the SSA Theorem be used to prove congruence?" and "When should we use Congruent Parts Congruent Triangles Congruent (CPCTC), and how does it prove anything?"
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 Triangle Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for finding the area, perimeter, etc. of an equilateral, isosceles, right, or scalene triangle.
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 Triangle: Proof  Michal Wojcik
A proof that the sum of the angles in a triangle is 180 degrees. This page is written in HTML with two graphical images.
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 Triangle Puzzle  Evelyn Sander, Geometry Forum Archives, The Geometry Center
Pick an arbitrary point in the interior of an equilateral triangle. Now go halfway towards one of the three vertices (you get to pick which vertex). Now you are at a new point in the triangle. Again go halfway towards any vertex. Continue this process.
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 Triangles and Pyramids: Playing Math!  Hollis Easter
A "teachable" on the construction of freestanding pyramids made "by folding a single piece of paper, with only a single piece of tape to hold them together...." This blog post goes on to include photos of a net, diagrams, and "things to investigate":
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 Triangles and Simplices (The Geometry Junkyard)  David Eppstein, Theory Group, ICS, UC Irvine
An extensive annotated list of links to material on triangles and their higherdimensional generalizations (simplices), with a particular interest in partitioning regions into triangles, tetrahedra, or higher dimensional simplices, for various applications
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 Triangles, Circles, And Waves  Kenny Felder
The site provides an overview of trigonometry. The material is merely
a refresher; only useful to beginners in trigonometry when used as supplementary course material in a trigonometry class.
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 Triangles in Elliptic Geometry  Thomas Banchoff, The Geometry Center
An examination of some properties of triangles in elliptic geometry, which for this purpose are equivalent to geometry on a hemisphere. The aim is to construct a quadrilateral with two right angles having area equal to that of a given spherical triangle.
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 Triangle with one 90degree Angle  NASA Lewis Learning Technologies Project
A triangle with one 90 degree angle is always: an equilateral triangle; an acute triangle; an obtuse triangle; or, a right triangle? A detailed answer is provided. From NASA's 9th Grade Math Proficiency Test.
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