oh well i got two answers – both different.
the first one was the one i predicted: That he learned to ask the questions in school. (of course he learned the answers too, but no one bothered to answer that)
then my dad said that it used to not be a written out hagada – they used to just ask at one point or another during the seder on their own. when they sat down and actually wrote out what people should say they put it in the beginning because it made sense according to the flow of things.
i should just add that my dad said there used to be a fifth question: Why do we eat only tzli (roasted) tonight?
they took it out later on because we don’t have korban pesach anymore.