Basic Facts
The basic facts of addition are all the combinations of pairs of numbers 0 through 9. The basic facts are defined as the combinations of numbers 0 through 9 because we have a base-ten numeration system with ten digits, or numerals, 0 through 9. Focusing on combinations of these numbers creates one hundred basic addition facts. Knowledge of these facts provides children with a firm foundation and is essential for learning how to use and make sense of the standard addition algorithm.

There are several strategies that children can use to learn their basic addition facts. Children may enter first grade with some strategies from Kindergarten, such as drawing a picture, using counters, or even counting on. The number-line model can also be used to provide children with a conceptual understanding of their addition facts.

The properties of addition can help make the learning of basic addition facts more manageable. The Zero Property of Addition and the Commutative Property of Addition can reduce the number of facts to be learned.

The Zero Property of Addition states that for every number a, a + 0 = a. Combined with the Commutative Property of Addition, which states that for all numbers a and b, a + b = b + a, the Zero Property of Addition simplifies learning the 19 facts involving 0.

The Commutative Property of Addition also eliminates children having to learn other facts. For example, once children learn that 7 + 2 = 9, it is easy for them to learn that 2 + 7 = 9. Applying the Commutative Property of Addition to the table simplifies learning another 36 facts. In general, children also find it easier to learn the doubles, or facts like 3 + 3 = 6. This leaves a total of 36 facts for children to focus their efforts on.

Teaching Model 5.3: Use Doubles to Add