Throughout out the series, it's clear that the actors/actresses portraying teenagers are actually in their 20s+. This is done as to not interfere with the schooling of real teenagers and to give the general viewing audience who are teenagers themselves someone they can look up to.
Throughout the first season Hanson repeatedly says "tail" when
his mouth obviously says "ass." This was a post-production change in response to network censorship, who thought the word "ass" was inappropriate.