Teaching how to add and subtract with an abacus helps children to see the process behind the operation. For an addition problem, 3 + 4 for example, slide three beads over to one side. Then slide over four more and count how many you have in total. For subtraction, begin with the first number and take the second number away, and count how many beads are left.
The idea behind multiplication can also be clearly illustrated using an abacus. To teach how to multiply by 2, have children slide over beads 2 at a time. For example, for the equation 2 x 4, have students move over four segments made of two beads each. Then count how many you have at the end. This also teaches children skip counting. As they move each segment over, tell them to count, 2, 4, 6, 8, and so on.
An abacus with 10 columns can be used to teach children about money and how much each coin is worth. Since there are 100 beads on this type of abacus, children can easily see how much of a dollar penny, nickel, dime or quarter represents by separating the corresponding number of beads from the rest. This can also be used to teach how to make change.
To get children even more involved in learning from an abacus you can teach them to create their own out of popsicle sticks, thin dowels and pony beads. Use the dowels as the columns and place the beads on them, then glue two popsicle sticks to the outside edges to hold them together.