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Mental Models for Adding and Subtracting

Videos:

• What Makes Addition Work?

• Doubling and Making Tens

• Two Digit Addition Strategies

• Compensation, Incrementing, & Transformation

• Using Number Lines for Addition

• Subtraction Foundations

• Compensation & Adding Up

• Constant Difference

When adding and subtracting, there are many ways we can transform the problem into one that is easier to solve mentally. These strategies can often be modeled using the number line.

When adding, strategies like compensation, incrementing, and transformation can be useful. When subtracting, strategies like compensation, adding up, and constant difference can be useful. These are not the only strategies students may use, but they are the most common.