Above their head - Idioms by The Free Dictionary
above (someone's) head (redirected from above their head)
above (someone's) head
Not understood by one because it is too complex or subtle for their comprehension. My jokes always seem to go above Stephanie's head, so I'm glad you think I'm funny at least.
above your head beyond your ability to understand.
above/over somebody’s ˈhead too difficult for somebody to understand: It was clear from the expression on his face that the lecture went completely over his head.