About the Abacus Arithmetic activity The module The Abacus Arithmetic module can be a two-part math night activity. You can have an abacus handy so that children can experiment with arithmetic on the abacus, doing the problems posed on the posters (and possibly similar problems posed by whoever is helping out with the activity) and building a shoe-box abacus. Either part could be done independently, also. Why have an abacus activity? The December 2001 issue (volume 8, number 4) of Teaching Children Mathematics features an abacus building activity in the "A Teacher's Journal" Column. Addition on the abacus reinforces number facility, place value, and regrouping. Children enjoy handling the abacus and using it to do computations. It is also still a practical calculating tool: it is used in shops and banks in parts of the world where calculators are not as readily available as in the US, particularly in parts of Asia. Building abaci The idea for building an abacus from a shoebox comes from MathArt Projects and Activities by Carolyn Ford Brunetto. I modified the instructions slightly in order to make the bar which goes accross the middle sturdier. I also reduced the number of strings to 4 in the interests of time: with four strings a first grade child should be able to build it in five to ten minutes. The modified instructions and equipment list are under Notes in the menu. Before encountering the shoebox idea I had made an abacus for use at home from poplar craft wood strips, 1 1/2" x 1/4", a coat hanger, and craft beads. The construction isn't suitable for a math night project because it is fussy work even for adult hands. It's an alternative to finding one and buying it. Here are the instructions: Cut two 9 1/2" long pieces from the craft wood for the top and bottom of the abacus. Cut a 9" long piece for the middle bar. Cut two 7 1/2" pieces for the sides. Drill seven evenly spaced holes all the way through the middle piece. Center the middle piece on the top and drill the seven holes partway into the top piece. Do the same for the bottom. Cut seven 7 3/4" lengths from a wire clothes hanger. Thread them through the holes in the middle piece. Put two beads on each wire above the middle and two beads on each wire below the middle. Add top, bottom, and sides. Glue top, bottom, and middle to sides with wood glue, clamp, and let dry. Photo of shoebox and wood abacus. A website on the abacus http://www.ee.ryerson.ca:8080/~elf/abacus/ Written by Janet A. Dixon 12/3/01 Revised 1/10/06