A teaching aid for signed numbers
Keyword(s):
Each year the time comes when it is necessary to illustrate the multiplication of signed numbers. There are many approaches to helping the student develop insight and skill. Some of the more common are multiplying two negative numbers using the number line, 1 * an inductive approach,2 the modern mathematical proof approach,3 the statement approach,4 or the model approach,5 but some young mathematicians still have a hard time understanding these ideas. The following is a very effective device which may be used to help students discover and then reinforce the operation of multiplication of signed numbers.