During the interview http://askobama.twitter.com/ at 42m20s, they claim that 10% of the questions are on Education, whereas twitsprout shows only 2% were on Education.
We may make the data set we gathered public some time, so people can draw their own conclusions about which categorizations are more accurate.
Now - I'm not trying to mock this, it's just sooo disconnected from all I know: Why do you ask questions, if you expect no answers? I see this here (moved to Israel) as well - strangers say hi and ask what's up - but don't care. At home, in Germany, I'd consider this not sincere. Yet, it seems to be quite the norm.