What classes can i take to be a pediatrician?

At the high school level, you will be taking science courses. Biology, Chemistry, and any pre-med courses your school offers. At the college level, you should be taking a pre-med slate, which is going to differ slightly at each university. Organic Chemistry, human biology, anatomy, genetics, and so on. Again, it will be a series of hardcore science courses and pre-med courses. You might want to take a bit of psychology as well to gauge where exactly your interests lie. You may also take some calculus and/or statistics.

Here's a link to some interesting Brown University pre-med guidelines: http://www.brown.edu/Administration/Dean_of_the_College/hco/first-year_sophomore/courses.shtml