If you've ever wondered why adolescents do some of the odd, impulsive things they do, you'll like this article,
"Inside the Teenage Brain." It summarizes some of the neurological findings on brain development and how it reflects in behavior.
For example, one small study seems to show that teenagers rely on an older, pre-mammalian part of the brain, the amygdala, to understand facial expressions, whereas adults use the reasoning cortex.
Most important, the use-it-or-lose-it feature of the brain implies that the earlier adolescents work on reasoning skills, the better.