Adding and Subtracting within 20
In this unit students • solve problems in all adding and subtracting contexts within 20; • make adding and subtracting strategies within 20 explicit.
Once students have a solid understanding of 10 as a bundle of 10 ones, they focus on addition and subtraction within 20. In this unit they solve problems in all adding and subtracting contexts within 20 and work to make their strategies for adding and subtracting explicit. One key strategy, making a ten, plays a prominent role in this work, as does the number line.
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