dAbacus

dAbacus is a free, easy program that simulates a Chinese abacus. As the user moves the beads, the Arabic numeral equivalents are shown. This allows students to deduce the values of the beads in different rows. One of the really cool features is that as the students use beads with smaller place values (i.e. two beads with a value of five each), they are exchanged for beads of larger values (i.e. one bead with a value of ten). This is a valuable exercise in teaching the concept of place value in a number system. This virtual abacus is a great virtual manipulative that can be used with a real abacus, as it provides students with immediate feedback as to the value of the beads.