Number and Operations Session 4: Notes

A B C

Notes for Session 4, Part C

Note 9

This model provides a visual image of the operations with signed numbers. You can literally see that the pairs of red and black chips cancel each other out, which gives you a sense of the magnitude of the answer. This works for all of the operations except division (but relating division to multiplication solves this problem).

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Note 10

This process can help you do subtraction of whole numbers using mental math. For example, to do 94 - 37 in your head, you might add 3 to both numbers. That gives you 97 - 40, which is easy to do in your head.

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Note 11

No model works for all computations, which is why we must not rely on models to do everything. Models provide a visual and kinesthetic feeling about the process, but eventually you must learn how to do the computation with symbols alone. It is important, however, to see the relationships between what you do with the models and what you do with the symbols.

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Session 4 | Notes | Solutions | Video