Why is 5+5+5=15 Wrong on Common Core Math Test

What is 5x3? 15 right. One 3rd grader, who answered 15, was deducted a point for getting it wrong. Why?

The Common Core test question was 5x3=?

The student answered 5+5+5=15

The teacher marked it wrong. Why?

The student should have answer 3+3+3+3+3=15

The question reads 5 groups of 3, rather 3x5, which would be 3 groups of 5.

It's the Common Core way of doing things to prepare students for more complicated math problems in the future. Parents aren't happy and are speaking out on Reddit, after one user posted a photo of the 3rd graders Common Core test.

Ultimately, this is a complaint about GRADES, not about teaching/learning math. Just look at the title. pic.twitter.com/gQRr8SW25D
— Frank Noschese (@fnoschese) October 21, 2015