Doubles and Near Doubles

Use 6 + 6 = 12 to know 6 + 7 = 13.

Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.

What children learn in Level 3

A double is a number added to itself, like 5 plus 5. Your two hands make a double: 5 fingers and 5 fingers make 10!
An egg carton shows 6 plus 6. Two rows of 6 make 12.
The doubles count by twos: 1 plus 1 is 2, 2 plus 2 is 4, 3 plus 3 is 6, all the way to 10 plus 10, which is 20.
Now look at 6 plus 7. It's almost a double! 7 is just one more than 6.
6 plus 6 is 12. One more makes 13. So 6 plus 7 is 13. That's a near double!
When two numbers are next to each other, like 8 and 9, double the smaller one and add 1. 8 plus 8 is 16, so 8 plus 9 is 17.

Georgia's K-12 Mathematics Standards:

2.NR.2.1 — Fluently add and subtract within 20 using a variety of mental, part-whole strategies.