Cannot or May not

Last night E was singing while she was flossing her teeth. So from the other room I say, "You can't floss your teeth and sing at the same time."

L, our astute second grader, realizing she can do it says, "Yes she can."

"Ok but she may not."

My second grader knows the difference between cannot and may not-- I however did not make myself clear.

dadFAIL