If he colors half of each of 4 segments (given 5 segments total), then why wouldn't it be 2/5? 4 halves = 2 wholes after all! I'm not sure why he would have gotten it wrong.
My DS5 got marked off last year in kindergarten for a problem that gave a number with blanks before and after and asked him to write one less and one more. He wrote them in descending order rather than ascending and the teacher thought that was wrong. The question didn't specify the order, just that you needed to write one less and one more. Sure, order may have been implied, but was he being tested on interpreting directions or on math? The same could be said for this boy.
I should not read these tiny monitors so early in the morning, and especially before I had my coffee! I misread it, you & OP's son are correct.
