Here's a "repeated addition" Common Core problem that's taught in third grade in US schools:
Use the repeated-addition strategy to solve 5x3.
If you answer the question with 5+5+5=15, you would be wrong.
The correct answer is 3+3+3+3+3.
Mathematically, both are correct. But under Common Core, you're supposed to read 5x3 as "five groups of three." So "three groups of five" is wrong.