A high school student asked how to pursue a passion for teaching and learning. My reply is below.
Hey, [name] -- sorry for the delay; I've been out of town and am still catching up on email.
If you want to teach and learn, go teach and learn. It doesn't have to be big or formal -- find someone (a family member, a friend, whoever) who wants to learn something you know, and teach it to them. They don't have to be academic subjects, either. It could be how to do basic chords on a guitar, or how to swing dance, or how to compare the taste of different chocolates, or how to play a video game. Notice what you do, what they got stuck on, how you explained it, how you modeled it -- then figure out what you learned about teaching from that, and then do it again (with the same thing, or a different one).
Pay attention to teachers, both bad and good. Critique them to yourself. If you can find a teacher who *wants* feedback and your thoughts on their curriculum and delivery, that's great -- maybe someone at school who takes their teaching seriously and would be willing to debrief with you after a class sometime, where you can tell them what you noticed and what you think they were attempting to do with it, and then they can tell you what they were thinking. Ask them how they think about teaching, but above all, observe.
All these fit into chunks around your free time. No need to make a regular commitment to a formal program, unless you find one you think you'll learn in, and want to do that. If you want to do something more involved, become a course assistant (I did this in high school, starting as a junior). It's stuff like making copies and starting the DVD player sometimes, yeah. But it gives you an excuse to hang around and watch and ask. What you're trying to get at is the things good teachers do, and why they do the things they do -- the responses they make in the moment, the thought process behind their actions. (No book can give you formulas on how to teach well -- only language to describe and communicate something you'll need to learn to live out by doing it in an apprenticeship.)
Hope this helps.