What models can be used to help explain the concepts of addition and subtraction of rational numbers? What are the benefits to using such a model? What limitations does the model have? Create an addition or subtraction problem and demonstrate how the model might work.
Cutting a pie into equal slices so you can add or subtract them.
EXAMPLE: 1/4 + 1/2 = 3/4. To get the half slice to equal the size of the quarter slice, you need to cut it in half. Then the half slice becomes two quarter slices. When you add all of the quarter slices together, you have three of them: the original quarter slice, plus two more from cutting the half slice in half to get two more quarter slices that you could add with the original to get a total of 3 quarters, or 3/4.