Make Ten is a key strategy for any addition facts with an 8 or a 9. We want students to think “How many more are needed to make 10?” and then “How many are left over?”
For example: 8 + 7
How many more are needed to make 10? 2!
If the 2 is taken from the 7, how many are left over? 5!
So, 8 + 7 is 10 + 5, or 15.
Key subskills are knowing how many more are needed to make 10 (bonds of 10), and how much is left after that step (-1 or -2). The near numbers one less and two less should be practiced using ten frames and dot plates. The near number page also has other strategies.
One way to help students record their thinking is to use branch diagrams to show how they partitioned the numbers.
This ability is also used in later years for multi digit computations, such as 28 + 7. It forms a key subskill in developing jump strategies for performing multidigit addition and subtraction.