 Boy or Girl?  Math Forum, a Classic Problem from the Ask Dr. Math FAQ
In a twochild family, one child is a boy. What is the probability that the other child is a girl? What if the older child is a boy?
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 The brachistochrone problem
 MacTutor Math History Archives
Linked essay on the brachistochrone problem, posed by Johann Bernoulli in Acta Eruditorum in June, 1696. With references and other related web sites.
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 BrainBashers  Kevin N. Stone
A collection of logic, language and math puzzles, in a choice of easy/medium/hard. Rate the puzzles; show their answers. Logic puzzles include Einstein's Puzzle. Play games of strategy, such as "Four in a Row" (also known as "Connect Four") or games based
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 BrainBashers  Kevin Stone
Five math or logic challenges on a page, each with clickable hints and solutions. For games, visit http://www.brainbashersgames.com/.
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 Brain Boosters  Discovery Education
An archive of challenging puzzles, organized under: Categorization, Lateral Thinking, Logic, Number and Math Play, Reasoning, Spatial Awareness, Word and Letter Play.
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 Brainers  PedagoNet
More than 60 word problems and puzzles designed to develop logic and problemsolving skills. Submit your answers and suggestions to become part of the Wall of Fame. Site is in English, French, and Spanish.
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 Brain Food  Puzzles For the Brain To Gnaw On  Samuel Stoddard
Hundreds of online (CGI) puzzles, including logic puzzles, word problems, number puzzles, lateral thinking puzzles, scrambled equations, cryptograms, loginumber puzzles, discrete reasoning puzzles, mathematical reasoning puzzles, knight's dilemma, magic
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 Brainfreeze Puzzles  Riley, Philip; and Taalman, Laura
Free example puzzles and solving tips for colorful, handdesigned Sudoku variation puzzles with additional rules that challenge you to rethink your old Sudoku strategies and devise new ones. From the authors of the book, Color Sudoku.
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 Brainingcamp Educational Math Software  Dan Harris, President and CEO
Real math problems and simulations for 5th9th grade. Middle school math online software. Guided by NCTM and State mathematics standards. Video demo and free trial available.
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 Brainly.com.br
"Estudamos em grupo." Faz perguntas; responde para ganhar rankings. Veja, em particular, o arquivo de dever e soluções na area de matemática.
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 Brain Science & ICT in Mathematics Education  Dave Moursund
An exploration of three major topics from a math education point of view: Brain Science Craft & Science of Teaching & Learning (C&S of T&L) Information & Communications Technology (ICT). Read the author's thoughts on constructivism,
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 Brainwave  Wognum Art
Ten visual puzzles, to test your visual and reasoning skills. Most have to do with symmetry recognition. There is a "top 5% brain" award to those who earn ten "smart bulbs."
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 Brainy Figuring  Ivars Peterson (MathTrek)
In the May 7 Science, Dehaene and collaborators at the Massachusetts Institute of Technology present the first hard evidence that two quite different modes of brain activity underlie our inborn capacity for mathematics. Their study indicates that learning
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 BreakTru Software  David Giordano
Math shareware and freeware downloads for the PC include Quick Conversion, which converts distance measures such as inches, feet, yards, rods, furlongs, miles, and leagues to and from metric units such as meters; Fractions n Decimals, which converts mixed
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 Bret Victor
From the creator of Kill Math, Victor's "umbrella project for techniques that enable people to model and solve meaningful problems of quantity using concrete representations and intuitionguided exploration" in pursuit of a "widelyusable, insightgenerating
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 Bricks Activity  Suzanne Alejandre
A classroom activity (also called the Masonry Problem; a variation on polyominoes) aligned to the NCTM and California Standards, to be explored through manipulatives (dominoes). Students explore different possibilities of making brick walls with and without
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 The Bridges of Königsberg  Jim Loy
A brief introduction to Euler's Bridges of Königsberg problem, graph theory, and simple related puzzles.
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 The Bridges Organization: art and mathematics  George W. Hart, Webmaster
The Bridges Organization oversees an annual conference on connections between art and mathematics. The site's virtual museum shows sculpture, paintings, drawings, digital prints, textiles, origami and other paperfoldings created by mathematicians and
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 Bridging The Gap  Nicora Placa
Blog by a former elementary and middle school math teacher pursuing a Ph.D. in teaching and learning. Posts, which date back to April, 2013, have included "The subway ad that changed my life," "Transforming the Teaching Profession: It starts with RESPECT,"
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 A Brief History of Algebra and Computing: An Eclectic Oxonian View  Jonathan P. Bowen; Oxford University Computing Laboratory, UK
Math history: Chapters on: The Origins of Algebra; Early English Algebra; Algebra and Analytical Engines; Boolean Algebra; Algebra and Computing; Recent Developments in the Algebra of Programs. References. Also available at http://www.museums.reading.ac.uk/vmoc/algebra/.
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 A Brief History of Cosmology  MacTutor Math History Archives
A hypertext essay describing the course of cosmology from its beginnings in early Babylonian society through the present, with References.
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 Brighten's Fractals Page  Brighten Godfrey
Investigate "Just Another Fractal Generator," a Java applet to make Iterated Function System (IFS) fractals based on triangles, or view a gallery of images created using the program.
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 Bring The Internet Into Your Classroom  NASA Quest Project
Links to an Internet Video Series designed to help teachers, administrators and community members introduce the Internet into K12 classrooms; grant information; which schools are online; and the universe of other NASA and Education Online Resources.
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 British Weights and Measures Association  Mr. Vivian Linacre, Edinburgh, UK
Views and aims; press releases; the association's publications and some articles from them; a list of patrons and officers; subscription details; an invitation to help; and contact information. "The British Weights and Measures Association opposes wanton
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 BrokenAirplane.com  Phil Wagner
Blog of "tips and ideas that you can use in your classroom immediately, and suggestions to help you, no matter your teaching or technology experience." Posts, which date back to June, 2010, have included "Math Project  Slope Art," "SAM Animation Is the
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 b's law  Brian Lawler
Blog begun March, 2011, by a professor of math education at California State University San Marcos. Posts, which "try to disrupt," have included "continued reaction to tracking," "The Problem of the Skateboarder Problem in IMP," "A Deconstruction of Learning
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 BUBL Link: Libraries of Networked Knowledge
A searchable national information service for the UK higher education community. Directory of UK organisations and institutions; Archive of LIS, journals, Internet development; abstracts, full text, hundreds of titles of journals; news: jobs, events,
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 Budgeting Money (SMILE)  Yolanda Smith, Douglass Math and Science Academy
A lesson for grades 68 designed to teach students how to budget a monthly income; basic math techniques integrated with reading and social studies skills; how to search for employment in the want ad section of a newspaper; and the difference between
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 Building a Virtual Museum Community  Jamie McKenzie
Virtual museums provide an excellent opportunity for museums to partner with schools. The Bellingham (WA) public schools recognized the potential of a partnership with the Whatcom County Museum of History and Art in Fall of 1995. This article describes
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 Building Big  WGBH Educational Foundation
Explore great feats of engineering and the ingenuity of the engineers, architects, and builders who designed and built them. Learn about bridges, domes, skyscrapers, dams, and tunnels; use Flash interactive engineering labs to experiment with forces,
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 Building Homes of Our Own  National Association of Home Builders (NAHB)
An interactive teaching tool for the middle and high school classrooms. The simulation presents a macro view of the entire home building process, from site selection to final sale. Students collect information, solve problems and make choices as they
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 Build Your Own Blocks  Mönig, Jens; Harvey, Brian
Turn, move, animate, and iterate figures with this visual programming language, which also lets you draw simple and complex fractals through recursion. Download Build Your Own Blocks (BYOB); watch tutorials; report bugs; and more. Originally designed
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 Bureau of Economic Analysis (BEA)  U.S. Department of Commerce
The nation's economic accountant, preparing estimates that illuminate key national, international, and regional aspects of the U.S. economy. Regional, national, and international data, articles, and products.
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 Burning 1Hour Fuses in 45 Minutes (Math Chat)  Frank Morgan, MAA Online
You have two onehour fuses: lighting one end of a fuse will cause it to burn down to the other end in exactly one hour's time. You know nothing else about the fuses; in particular you don't know how long any segment of a fuse will burn, only that an
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 Burnt Toast Publishing  Bran McMillin
Burnt Toast Publishing offers the math puzzles for free use.
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 BusinessHigher Education Forum  BusinessHigher Education Forum
BHEF is an organization of Fortune 500 CEOs, prominent college and university presidents, and foundation leaders working to advance innovative solutions to education challenges in order to enhance U.S. competitiveness. BHEF addresses education issues
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 ButlerCooley Excellence in Teaching Awards  Turnaround Management Association (TMA)
This program, made possible through the John William Butler Foundation, honors elementary and secondary grade teachers who have demonstrated exceptional dedication and skill in shaping the lives of students and the communities in which they live. It awards
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 The Butterfly Website Picture Galleries  Mikula Web Solutions, Inc.
Symmetry in nature: butterfly and moth images from a variety of sources. In most cases, a small picture is included for speed of transmission, and a larger picture is available by clicking on the small picture.
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 Byte Works, Inc.
Developers of the apps iPhone Calculator, a scientific/logic/conversion calculator; and techBASIC, which takes advantage of the iPod's, iPhone's, and iPad's builtin accelerometers, gyroscopes, or magnetometers to collect information, process it with
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 By the Numbers  Kinder Magic Software
Practice basic consumer math skills with Java applets that pace you though arithmetic problems, step by step: addition or subtraction of whole numbers or of decimals, percent markup, multiplication by one and twodigit numbers, multiplying decimals,
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 Cable's Leaders in Learning Awards
Cable's Leaders in Learning Awards recognizes outstanding educators, administrators, policymakers, and other community leaders at the forefront of innovation in education. Award categories include: Cable Partnerships for Learning, Pushing the Envelope
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 Cabri Geometry: Classroom Resources  The Math Forum
The Math Forum's page of links at the Forum and on the Web to dynamic interactive geometry classroom resources for Cabri Geometry. Books and Web sites; Frequently Asked Questions; exploring the basics; workshops; excerpts from the journal abraCAdaBRI;
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 Cabri Jr.  Texas Instruments Incorporated
Interactive geometry for the calculator: construct, analyze, and transform mathematical models and geometric diagrams. Cabri Jr. imports and exports figures from Windows computers. Take a tutorial, preview and download weekly activities, or browse the
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 Calchemy Live!  Calchemy Software Inc.
Express the parameters of an equation in any convenient units of measure. Calchemy then checks the equation and parameters for dimensional consistency and makes all the necessary units conversions automatically. Categories include acceleration, angle,
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 CalculateHours  Molly Parker
This online time card calculator calculates hours worked. Add the widget to your site by copying the code provided. Training sessions teach how to use Excel to add up hours, average hours, and convert decimal hours or military time into conventional hours.
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 Calculate the Distance Between Two Places  infoplease.com
How far is it from one place in the U.S. to another? As you type, this form automatically completes the names of populated places, schools, "locales," parks, islands, bars, lakes, reservoirs, bays, gaps, dams, glaciers, streams, wells, mines, bends, valleys,
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 CalculateWhat  Colin Fagras
Free online calculators. In addition to covering math topics such as algebra, geometry, and statistics, CalculateWhat crunches numbers on topics financial, scientific, and  under a category called "miscellaneous"  more whimsical and topical in nature.
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 CalculationRankings  Youri Lieberton
Arithmetic problems to solve or number sequences to complete as a stopwatch counts down. Play the games to compare high scores against other speedy problem solvers; take the timed tests to see correct answers after submission.
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 Calculations and Formulas for Gemstones  Dendritics Incorporated
Calculate the carat weight or specific gravity of a gemstone or the value of precious metals in various currencies, or convert weights among grams, carats, pennyweights, and ounces.
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 A Calculator
JavaScript calculators: the four basic operations, average, arithmetic congruence, greatest common divisor (GCD), least common multiple (LCM), radical simplifier, word converter that writes out numerals, and more.
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