NA2-3: Know the basic addition and subtraction facts.

Elaboration on this Achievement Objective

This means students will know the basic addition facts from 0 + 0 = 0 to 9 + 9 = 18. So 4 + 1 = 5, 8 + 6 = 14, and 9 + 3 = 12 are all basic addition facts. The basic subtraction facts are the subtraction equivalent of the addition facts, so 5 – 1 = 4, 5 – 4 = 1, 12 -3 = 9 and 12 – 9 = 3 are all examples. It is important that students understand the commutative property of addition (for example, 4 + 7 = 7 + 4), and the inverse nature of addition and subtraction (for example, 6 + 7 = 13 so 13 – 7 = 6), as a foundation for more difficult problems, as well as a way to connect basic facts. Students also need to encounter the unknown in different positions within their basic facts, for example, 4 + box. = 12 and  box.  – 5 = 8.