Sharing ideas for teaching math in the middle school.
Thursday, November 12, 2009
Tool for Multiplying and Dividing with Integers
This is a simple visual tool to help struggling students when multiplying and dividing with integers. I have students create a tic-tac-toe board in the upper corner of their papers. On the diagonal, students put in + signs, and the rest is filled in with - signs as shown. Reading along the top line for example, is a visual tool for students to see that a positive number times a negative number equals a negative number. It works for division too. Going down from the upper left corner, you will see that a positive number divided by a negative number equals a negative number. Reading along the diagonal you will notice that a positive times a positive equals a positive. This works reading the tool backwards/upside down too! The top row backwards would indicate that a negative number times another negative number equals a positive number. Most of my students have found this simple visual strategy helpful when working with integers. I notice it on homework assignments all the time.