In Math, the sixth graders have been working with positive and negative integers. Addition of integers was introduced with Cecil, an acrobat who can move forward and backward on a tight rope. Using their computers, the students investigated how Cecil could travel along tight ropes of different lengths. They had to combine positive and negative integers to successfully navigate the increasingly difficult challenges.
To continue this idea, Mr. Zippin introduced Integer Tiles. The Integer Tiles are small plus and minus pieces that represent positive and negative one. By laying out 5 plus tiles, we represent the number 5. If we lay out 3 minus pieces, we represent the number -3. By combining these eight tiles we are representing the expression 5 + (-3). The students noticed that the three plus pieces, when combined with three minus pieces made three zeros. After discussing the identity property of addition, they knew that adding these three zeros did not change the sum so the total value of the expression was 2.