Before my daughter started school, I read news articles and viral Facebook posts about Common Core math questions. One question was 5 × 3 = 15. The student was penalized because he answered 5 + 5 + 5 instead of 3 + 3 + 3 + 3 + 3. Here’s the link to the article.
At the time, I thought that it was really stupid. Now, my daughter has been in school for more than a year, I have bought multiple math programs based on Common Core math, I have read the standard itself… and it seems like a lot of the Facebook posts that were supposedly Common Core math were not, in fact, Common Core math. This is why it is important to read the standard itself. Here’s the link to the Common Core State Standards Initiative for your reference.
As for the problem above, Common Core specifies the commutative property of multiplication so the student’s answer is right.
Apply properties of operations as strategies to multiply and divide.2 Examples: If 6 × 4 = 24 is known, then 4 × 6 = 24 is also known. (Commutative property of multiplication.) 3 × 5 × 2 can be found by 3 × 5 = 15, then 15 × 2 = 30, or by 5 × 2 = 10, then 3 × 10 = 30. (Associative property of multiplication.) Knowing that 8 × 5 = 40 and 8 × 2 = 16, one can find 8 × 7 as 8 × (5 + 2) = (8 × 5) + (8 × 2) = 40 + 16 = 56. (Distributive property.)