from Spring 97 issue

by Debra Sewell, TSBVI

Parents of many children with visual impairments are familiar with "talking calculators" and understand how their child can use this adaptive device to aid him/her in doing math problems. However, there is an ancient device they may not be aware of that is very important for their child to be able to use. This device is an abacus and is an adaptation of the Japanese abacus. Most of you have seen an abacus somewhere in your life, but you may never have used one. For the child with a visual impairment the abacus is comparable to the sighted child's pencil and paper, and should be considered a fundamental component of his math instruction. Just like his sighted peers, the VI student should also learn to use a calculator. Total reliance on the calculator should be avoided, however, because 1) the calculator does not allow a child to learn problem-solving skills, 2) the VI child will not have a "backup" plan when the battery goes dead. Additionally, children who are deafblind and who may not be able to hear the voice of a talking calculator, may also benefit from using an abacus.

Tactual learners may find it easier to use a device like an abacus. Some VI teachers do not teach abacus until students know their number facts to ten. In fact, the abacus can be used without knowing number facts to ten when the counting method is used.

### How to Use the Counting Method

Similar to Chisenbop (a system of using fingers for calculating), the counting method uses rote counting as beads are moved toward or away from the horizontal counting bar of an abacus.

As compared to other methods of calculating on the abacus (synthesis, direct/indirect, secrets, number partners), the counting method involves only four processes. Consequently, this method is best for students with visual and multiple impairments who would benefit from using an abacus. These students will probably learn the four processes more easily than the many steps needed to complete calculations with other methods. To be successful using the counting method, students should be capable of rote counting and have the knowledge of the concepts "one more than" and "one less than."

### Abacus Counting Method

4/5 exchange = exchanging a 5-bead for four beads set in the same column

Example: When you have four beads set and need to add one more, you set the 5-bead above the bar in the same column as you clear the four beads and count "one."

0/9 exchange = exchanging beads equaling the amount of nine for a 1-bead in the column to the immediate left

Example: When you have the amount of nine set and need to add one more, you set a 1-bead in the column to the immediate left as you clear the nine and count "one."

49/50 exchange = exchanging beads equaling the amount of 49 for a 5-bead in the same column in which the four beads are set

Example: When you have the amount of 49 set and need to add one more, you set the 5-bead in the same column in which the four beads are set as you clear the 49 and count "one."

99/100 exchange = exchanging beads equaling the amount of 99 for a 1-bead in the column to the immediate left

Example: When you have the amount of 99 set and need to add one more, you set a 1-bead in the column to the immediate left as you clear the 99 and count "one."

These exchanges are reversed for subtraction and can occur in any column on the abacus.

Reprinted with permission from TSBVI.

Taken from Teaching Students with Visual and Multiple Impairments by Millie Smith and Nancy LeVack, 1996.