I would say that a major issue is that schools have been spending less time on other activities. Music, Art, and Gym are courses that can really draw the students attention and keep the mind active. Keep the kids interested in what they're doing at school and they may just sick around.

I've heard that some schools in the states started dropping those courses to focus more time on Math, Science, and English. If that's true, I would say it was a big mistake.

Edit: Even courses like Shop, Cooking, Electronics, are very beneficial. Having one of those courses as mandatory per semester would be great. It was like that for me in junior high and I loved it.