 Randomness and Geometric Probability (The Geometry Junkyard)  David Eppstein, Theory Group, ICS, UC Irvine
An extensive annotated list of links to material on randomness and geometric probability: Buffon's needle; random domino tilings; random polygons, etc.
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 random.org  Mads Haahr
Generate random numbers on the Internet by using a web form (comparable to throwing dice), randomized sequences (lottery tickets), raw random bytes, virtual coin flips, or bitmaps. All numbers are tested statistically and the results available in realtime.
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 RapidCalculator  ProAlgorithms.com
This mobile computing platform for web and handheld devices performs matrix operations like multiplication/inverses; plots graphs of functions and operations on polynomials; manipulates complex numbers; and evaluates other math, science, and engineering
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 Ratio and Proportion  NASA Lewis Learning Technologies Project
If the ratio of boys to girls is 5 to 8 and there are 40 girls, which proportion should you use to find out the number of boys? A detailed answer is provided. From NASA's 9th Grade Math Proficiency Test.
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 Ratio and Proportions (SMILE)  Barbara Trotter, Ole A. Thorp School
A lesson designed to teach students to read and write proportions; identify the means and extremes of a proportion; solve proportions and problems using proportions; and to make a scale drawing. From the Practical and Applied Math section of a collection
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 Rational Functions: Oblique Asymptotes and Real World Applications  Jay Yohe; Susquehanna Township High School, Harrisburg, PA
A description of the oblique asymptote in rational functions, with a review of the necessary steps for graphing rational functions. In addition, two realworld application problems are explored involving cost and dimensions of cans and reduction of acid
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 The Rational Mean  Domingo Gomez Morin
Blog by a Venezuelan engineer. See, in particular, Morin's arithmonic mean and other original methods for approximating the roots of algebraic equations.
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 Ratios (SMILE)  Richard Murray, Gage Park High School
A lesson that uses scale models to teach students to examine models and compare their lengths numerically; to measure the models; and to calculate the length of the real size base when they know the scale of the model. From the Practical and Applied Math
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 Raw  DensityDesign Lab
The "missing link between spreadsheets and vector graphics," this open web app's interface lets you create custom vectorbased visualizations on top of the DataDriven Documents JavaScript (D3.js) library. Starting with delimiterseparated values in plaintext
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 rawsonmath  Pamela Rawson
Blog by a math teacher at STEMfocused public charter high school. Rawson, who worked for 25 years in traditional public high schools in and around southern Maine, describes herself as "still learning." Posts, which date back to August, 2012, have included
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 The R. Buckminster Fuller FAQ  Christopher J. Fearnley
The Frequently Asked Questions and Answers (FAQ) Resource on R. Buckminster
Fuller, based primarily on the history of the discussions, interests, and needs of the readers of the BITNET mailing list Geodesic and its USENET gateway bit.listserv.geodesic.
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 R. Buckminster Fuller on PBS  Thirteen / WNET
A biography of R. Buckminster Fuller, with explanations and illustrations of inventions such as the Dymaxion house, Dymaxion car, Dymaxion bathroom, and geodesic dome. Explore Fuller's Dymaxion map, John Kuhtik's Fly's Eye Dome, the World Game, and the
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 R. Buckminster Fuller's Octet Truss  Hop David
A discussion of Buckminster Fuller's invention based on the octahedron/tetrahedron tessellation.
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 Readings and Poetry Selections for Mathematics in Poetry  JoAnne Growney, Bloomsburg Univ., Bloomsburg, PA; The Math Forum
Annotated bibliography for the contributed paper session, "The Scholarship of Humanistic Mathematics," AMSMAA Joint Meetings, Orlando, Florida, 1996.
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 Real Numbers in the Real World (SMILE)  Ulysses Harrison, Dunbar Vocational High School
A lesson designed to teach students to group the set, R, of real numbers into two different sets: R > 0, R < 0; use parentheses to change the order in which
exponentiation, multiplication, division, addition and subtraction are performed
by
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 Real Teaching Means Real Learning  David Martin
Posts from this blog, which date back to November of 2010, have included "Calculus and the justice system," "Driving and deriving in math class," "BEDMAS last along with Lottery Winners," and "Meaning first, homework second." Martin, who teaches high
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 Real World  Lesson Ideas: Math; Teachnet.Com
Activities: Buy Groceries; Plan Christmas Vacation; Credit Cards for Kids; Who's Average?; Carpet Your Classroom; Division from a Printer's Viewpoint.
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 Real World Math  Thomas J. Petra
Lessons that use Google Earth to teach math include Oil Spill Estimates and Scientific Notations; Iditarod Challenge and Typhoon Project; Four Color Map and Mazes & Labyrinths; Crop Circles and Fractal Measurement; Lunar Sports and Rockets. Each lesson
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 Real World Math Via the Internet  Wendi Fein, M.A., Heritage Online
K12 math using real world problems and data that will support interdisciplinary teaching of science, social studies, history and business. Teachers in this course take advantage of the Internet for class discussions and to access material, and prepare
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 The Real Y2K Problem (Math Chat)  Frank Morgan, MAA Online
Solution to the challenge: Every year in the millennium from 2000 to 2999 can be represented as the sum of consecutive integers, except one year. Which year cannot be represented as the sum of consecutive integers? New challenge: Where do you think you
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 Reasons for Studying (Learning and Mathematics)  Susan Bobbitt Nolen; Math Forum
In this 1988 article, "Reasons for studying: Motivational orientations and study strategies," Susan Bobbitt Nolen, of the University of Washington, argues that in order to foster meaningful learning and effective study strategies, teachers should reduce
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 Reassessing U.S. International Mathematics Performance: New Findings from the 2003 TIMSS and PISA  American Institutes for Research
"Despite a widely held belief that U.S. students do well in mathematics in grade school but decline precipitously in high school, a new study comparing the math skills of students in industrialized nations finds that U.S. students in 4th and
8th grade
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 Recent Earthquake Teachable Moments  Incorporated Research Institutions for Seismology (IRIS)
Incorporated Research Institutions for Seismology (IRIS) is a university consortium sponsored by the National Science Foundation (NSF), dedicated to the operations of scientific facilities for the acquisition, management, and distribution of freely available
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 Recherche dans MATHS France  Académie de Toulouse
Un moteur de recherche qui scanne tous les sites académiques en mathématiques.
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 Recipes for Pi  Anna Weltman
Blog born partly "out of a mixture of enthusiasm and anger about the ways that the world learns and shares math." Posts, which date back to February, 2012, have included "Tinker, Tinker, Algebra Student"; "Beauty Is a Math Art Class"; "The Mathematics
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 Recommended Mathematics Literature  International Mathematics Olympiad (IMO)
A page of readings recommended by the International Mathematics Olympiad in association with Amazon.com Books. Major sections include: Problem Solving; Collections of Mathematical (Competition) Problems; Anthologies and Surveys; Number Theory; Analysis;
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 The rec.puzzles Archive
The index of the rec.puzzles archive. Puzzles are categorized by subject area and include solutions compiled from various sources and supposed to be definitive. Subjects include: analysis, arithmetic, combinatorics, competition, decision, geometry, group,
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 The rec.puzzles Archive  Massachusetts Institute of Technology (M.I.T.)
A list of puzzles, categorized by subject area, from the newsgroup rec.puzzles. Puzzles include solutions compiled from various sources, supposed to be definitive. Subjects include analysis, arithmetic, combinatorics, competition, decision, geometry,
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 rec.puzzles FAQs by Newsgroup  Dept. of Computer Science, Universiteit Utrecht
Information on the following topics: crosswords, analysis, arithmetic, combinatorics, competition, cryptology, decision, geometry, group, induction, Instructions, language, logic, physics, Pickover (Cliff), probability, reallife, references, series,
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 Recreational Mathematics  David Eppstein, Theory Group, ICS, UC Irvine
Some Web resources for recreational math, including links to Eppstein's pages own (Number Theory, Combinatorial Game Theory, and The Geometry Junkyard) and to pages by others.
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 Recreational Mathematics Topics  Steven Dutch; University of Wisconsin  Green Bay
Contents: Symmetry, Crystals, Polyhedra and Tilings: an extensive, illustrated collection including reflectional and rotational symmetry; repeating patterns in two and three dimensions; building crystal forms with unit cells; regular, Archimedean, radial,
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 Rectangle Pattern Challenges  Cynthia Lanius
Examine different stges of rectangle patterns, and describe what you must do to get from one to the next. Observe the designs looking for patterns. Use the symmetry of the design to help you count. Organize your information into a table. On square grid
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 Rectangle Perimeter and Side Length  NASA Lewis Learning Technologies Project
A rectangle with a perimeter of 24 inches might have adjacent sides measuring: 6 inches and 4 inches; 11 inches and 13 inches; 9 inches and 3 inches; or, 2 inches and 12 inches? A detailed answer is provided. From NASA's 9th Grade Math Proficiency Test.
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 Rectangular Parallelepiped, Cube Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for finding the surface area and volume of a rectangular parallelepiped and a cube.
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 Rectilinear Geometry (The Geometry Junkyard)  David Eppstein, Theory Group, ICS, UC Irvine
An extensive annotated list of links to material on geometric problems defined on squares and rectangles, higher dimensional boxes, cubes, and hypercubes, right triangles and other rightangled figures, and "taxicab geometry" in which distances are measured
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 A Recursive Process  Dan Anderson
Anderson's blog, which dates back to June of 2010, has included posts such as "Robocode & Math," "Standards Based Grading," "Cake:Frosting (A look into a proper ratio of real math:cool tech)," "Paper Towels WCYDWT (What Can You Do With This?)," "Two
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 Recursos de Matemáticas en Internet  Flavio P.
Información buscable, dividida en categorías que contienen enlaces comentados: altas, actividades, actualización, apuntes, buscadores, congresos, debate, enlaces, Escher, fractales, historia, lista general, Olimpiadas, publicaciones,
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 Recycling Topology  Ivars Peterson (MathLand)
It's hard to miss the triangle of three bent arrows that signifies recycling. It appears in newspapers and magazines and on bottles, envelopes, cardboard cartons, and other containers. But have you noticed that there are two versions of this ubiquitous
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 Redecorator Fractal Wallpaper Manager  Seraline P/L, Sydney, Australia.
A wallpaper manager, or randomizer, and image creator for Windows 95/98/NT/2000. Redecorator can change your desktop wallpaper as often as you like, creating seamless tiles and fractals.
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 Reference Notes  Department of Mathematics, Cal. State U. San Bernardino (CSUSB)
Notes on set theory, symbolic logic, methods of proof, basic proofs, functions, relations, binary operations, and groups. Also, Math Tools for practicing modular arithmetic and truth tables, or for solving Diophantine equations. Search the Notes, or scan
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 Reflections in the Plane  Bridget Dunbar
Blog by an instructional resource teacher in a middle school in Maryland. Dunbar describes herself as having "loved math my entire life" and a person who does not "remember having a bad teacher — only teachers who made me love math more. I even
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 Reflections in the Why  Chris Hunter
Blog by a K–12 numeracy helping teacher in Vancouver. Posts, which date back to September, 2010, have included "Linear Functions — Concretely, Pictorially, Symbolically"; "Math Manipulative of the Month — Base Ten Blocks"; "A Linear Functions
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 Reflections of a High School Math Teacher  Dave Sladkey
Blog by a teacher at Naperville (Illinois) Central High School. Posts, which date back to March, 2008, have included "Thinking Blocks," "School is a Place to Learn from your Mistakes," "More on When Students Teach," "Pop Goes the Weasel and the Quadratic
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 Reflections on Deep Blue  Keith Devlin (Devlin's Angle)
We generally assume that the ability to play a good game of chess requires intelligence when it comes to people. Why not for chessplaying machines as well? Well, here is one argument that shows that things are not so simple. One aspect of human intelligence,
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 Reflections on Holes in Graphs and Reasoning  Zach Cresswell
Blog by a Michigan teacher of AP Calculus, Precalculus, and Algebra II who has taken graduate courses such as "Creativity in Teaching & Learning." Posts, which date back to May, 2013, have included "Trying a bit of '3 Act Math'"; "Multiple Methods for
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 Reform Calculus Resources  Harel Barzilai
Many printable activities and worksheets, some with solutions, longterm student projects, capsules and tutorials, and resources for instructors including a sample secondsemester calculus course with inclass groupwork activities, projects, and student
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 Regression Applet  R. Webster West, Dept. of Statistics, Univ. of South Carolina
An applet designed to teach students the effect of leverage points on a regression line. Students may add points to the plot by clicking the mouse button. By adding points far from the existing line, the regression line changes considerably. This is particularly
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 Regular Polygon Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for finding the area, perimeter, etc. of a regular polygon, and constructing regular polygons with compass and straightedge, in particular the pentagon.
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 Regular Polyhedra: Formulas (Ask Dr. Math FAQ)  Math Forum
Formulas for finding the surface area, perimeter, volume, etc. of regular polyhedra: tetrahedron, cube, octahedron, dodecahedron, icosahedron.
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 ReInventing FourthGrade Mathematics  Jack J. Lopez; Kodak
A series of four related activities through which students acquired a firm, active knowledge of some of the basic terminology of Euclidean geometry, learning the vocabulary for describing various geometric shapes and transformations. Students photographed
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