binip, I could understand if the problem asked for an explanation. It didn't. He has to answer True, False, or ?. There was hardly any space to "show" that 20-12=8*3 is 8 =/=24.

For other problems on the worksheet, there were lines beneath each problem for students to provide written explanations.

It is absolutely appropriate to require students to understand concepts and be able to articulate them. I don't know that this worksheet is a good example of that--not in 4th grade.