It may just be his rebellion. My DD5 doesn't like to be put on the spot sometimes and will not answer or give wrong answers intentionally as a form of rebellion. I know that is the case because if I said, "I'll give you a cookie if you tell me" (I don't do this LOL) she would say the right thing immediately ;-)
That said, there are times their brains short out and they say the wrong thing or can't remember things. I am working on being gentle with my DD5's mistakes since I am a perfectionist and she is too. I am also trying not to "quiz" her unless she asks to play guessing games or a quiz type game.
