Students are funny sometimes

A student came to see me today looking very serious. He explained that he got zero for a certain part of the assignment and wanted to know why. Then he said:

I implemented something different.  Do I actually have to  make it do what the specification says?

Ummm, YES! Hello? Just what do you think is the point of this entire course?

Sigh, I really wish I could actually say that to students instead of just thinking it.