What is the most efficient strategy for solving 8 + 6?
ACount up from 1: 1, 2, 3, ... all the way to 14
BCount on from 8: 9, 10, 11, 12, 13, 14
CMake ten: 8 + 2 = 10, then 10 + 4 = 14
DGuess and check
Making ten (option C) is generally the most efficient strategy for sums near 10. You decompose 6 into 2 + 4, use 2 to bring 8 up to 10, then add the remaining 4 to get 14. Counting on (option B) also works but requires more steps. Counting from 1 (option A) is the least efficient strategy and the one students should move beyond.
Question 2 True / False
7 + 9 gives a different answer than 9 + 7 because the order of the numbers changes the total.
TTrue
FFalse
Answer: False
This is the commutative property of addition: changing the order of the addends does not change the sum. 7 + 9 = 16 and 9 + 7 = 16. Recognizing this property is useful because it lets you always start with the larger number when counting on, which requires fewer steps.
Question 3 Short Answer
Why is counting on from the larger number better than always counting on from the first number given?
Think about your answer, then reveal below.
Model answer: Counting on from the larger number means you take fewer steps. For 3 + 8, counting on from 8 takes 3 steps (9, 10, 11), but counting on from 3 takes 8 steps. Fewer steps means less chance of losing track and a faster answer.
This connects directly to the commutative property: since 3 + 8 = 8 + 3, you can always reorder and start from whichever number is larger. The strategy reduces working memory load and counting errors.