What could possibly have been Philip Chism's motive?

[youtube=http://www.youtube.com/watch?v=f6fD8D17dgk&w=600&h=315]

This is probably one of the more f'ed up stories of the year. You can read about all over the Internet, although the basic story is as follows: 14 year-old student murders 24 year-old teacher, presumably with a box cutter. He uses a recycling bin to move the body to woods behind the school.…