I know a lot of people are calling for education reform, and I thought I would throw my two cents in.
1. Grammar. In my experience, grammar gets taught to 8-10 year olds, and it gets completely ignored in older grades and high school. I think it would be better if high schoolers learned more about grammar, because they would certainly have an easier time understanding infinitives and gerunds than fifth graders.
2. Vocabulary. In my school, vocabulary lists were always taken from whatever book we happened to be reading. This can result in highly specialized vocabulary. For example, if you read Catch 22, you're likely to get a lot of military words. It would be better if vocab focused on words children need to know, not just whatever words happen to be nearby.
I know that The Cat in the Hat was written, in reference to a teachers' vocab list of words young readers need to learn. I'm sure there is a similar list for older children.
3. Math. Math is great, but I feel like it gets too advanced. I mean, I liked calculus and trigonometry, but I have never used those things outside of a math classroom. Meanwhile, my girlfriend who works with the IRS encounters people who can't add and subtract on a daily basis. So perhaps math classes should work extra-hard on drilling in fundamental math, instead of focusing on the more advanced and abstract math.