 The ABACUS International Math Challenge  Tivadar Divéki, Grace Church School
The ABACUS International Math Challenge is open to students in three categories (grades 34/ages 910; 56/ages 1112; 78/ages 1314), with 8 problems posed each month. The challenge begins in September and ends in April. It originated with the ABACUS Math Challenge started 5 years ago in Hungary by Sándor Róka, for students in grades 48.
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 A+ Math
A site developed to help elementary school students improve their math skills interactively, offering: educational math games (learn basic operations and geometry by playing MATHO  bingo and math combined; Hidden Picture; and Concentration), Web flash cards for practicing rounding, area, square roots, inequalities, fractions, counting money, geometric shapes; and Homework Helper, which lets you enter your addition, subtraction, multiplication or division problem and your answer, then checks to see if it's correct. Also Advanced Problems which allows you to select the kind of problem you want to practice and checks your answers.
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 BEATCALC Archive  Math Forum
An archive of B. Clay's BEATCALC weekly mailing list. Amaze your friends by memorizing a few simple rules and doing mental math tricks faster than they can do them on a calculator. Squaring, multiplying, dividing, adding, and subtracting numbers; finding percents; calculation practice exercises.
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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 fault lines, using diagram, process, and solution in their problem solving. A teacher lesson plan is provided.
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 Cryptarithms  Interactive Mathematics Miscellany and Puzzles, Alexander Bogomolny
Cryptarithms are brain teasers obtained when digits in numerical calculations have been replaced by letters. Customarily, distinct letters stand for different digits. Another term, Alphametics, denotes cryptarithms in which letters form meaningful words, often in meaningful phrases [i.e., son to father: SEND + MORE = MONEY, and father to son: SPEND + LESS = SONNY]. This site offers Java implementations of various cryptarithms and alphametrics, as well as the opportunity to send in your favorites.
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 Flash Cards for Kids  Donovan Follette
Currently, Flash Cards (shareware for Windows) supports addition, subtraction, and multiplication. The addition facts are enabled in the download file. The subtraction and multiplication facts can be enabled with a registration fee of $12.00. (Washington state residents must include an additional 90 cents to cover the 7.5% sales tax.) Flash Cards records the fastest times for any number of players. When a player begins a new card set, the timer begins. Once the last card in the set has been answered, the new time is compared with the old and messages are given accordingly. If the new time is faster, then it becomes the new target time for the set. Since children have varying levels of computer skills, Flash Cards receives its input from the mouse, keyboard, or a 10key pad.
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 K12 Teaching Materials (Mathematics Archives)  University of Tennessee, Knoxville (UTK)
An extensive list of Internet sites with significant collections of materials that can be used in the teaching of mathematics at the K12 level. Organized into categories: lesson plans, schools, software and other K12 Internet math sites.
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 Kids' Place Brain Teasers  Houghton Mifflin Company
Math puzzles for grades 34, 56, and 7+. You don't need to be a math whiz to solve them, just to be patient and find different ways of looking at things. New puzzles and the answer to the previous week's puzzles are posted each Thursday. Helpful hints and an archive are included.
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 Locker Problem  Suzanne Alejandre
A classroom activity (also called 1000 Lockers) aligned to the NCTM and California Standards, to be explored through the use of manipulatives and a ClarisWorks spreadsheet. Students then look for patterns and write the answer algebraically. The problem: imagine you are at a school that still has student lockers. There are 1000 lockers, all shut and unlocked, and 1000 students. Suppose the first student goes along the row and opens every other locker. The second student then goes along and shuts every other locker beginning with number 2. The third student changes the state of every third locker beginning with number 3. (If the locker is open the student shuts it, and if the locker is closed the student opens it.) The fourth student changes the state of every fourth locker beginning with number 4. Imagine that this continues until the thousand students have followed the pattern with the thousand lockers. At the end, which lockers will be open and which will be closed? Why? A teacher lesson plan is provided.
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 Magic Squares: Math, History, Geography  Suzanne Alejandre
Designed primarily for middle school and older elementary school students, this Math Forum Web unit includes classroom activities for four different squares: Lo Shu, Sator, Dürer, and Franklin, three of them demonstrating increasing complexity using numbers, and one made up of letters, with number and symmetry questions and links and suggestions for history / geography / writing activities for teachers interested in interdisciplinary work. Includes directions for building magic squares, definitions, discussion of some special properties of magic squares, a Java applet, and links to other magic square Web sites.
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 Tangrams  Tom Scavo
Tangrams, a puzzle that helps develop spatialvisualization skills, may also be used to introduce or reinforce geometric concepts such as congruence, similarity, symmetry, etc. This unit for grades 4 through 6 uses tangrams to compute the area of polygons without formulas, introducing the terms congruent and similar. Contents: Constructing Your Own Set of Tangrams; The Area of Tangram Pieces; More Tangram Activities. Links to other tangram resources on the Web are also provided.
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 Traffic Jam Activity  Suzanne Alejandre
A classroom activity (also called Hop, Skip, Jump) aligned to the NCTM and California Standards, to be explored through large movement experience, manipulatives, and an interactive Java applet. Students then revisit the activity, look for patterns, and write the answer algebraically. The activity: there are seven stepping stones and six people. On the three lefthand stones, facing the center, stand three of the people. The other three people stand on the three righthand stones, also facing the center. The center stone is not occupied. Everyone must move so that the people originally standing on the righthand stepping stones are on the lefthand stones, and those originally standing on the lefthand stepping stones are on the righthand stones, with the center stone again unoccupied. A teacher lesson plan is provided.
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