<p>Either way, college or HS instructor, you need to get a B.S. in Chemistry. (or whatever science). The education training component would generally be part of a 5 year BS/MS or a separate MS. So you can adjust your major and then toward junior year figure out if you are interested in H.S. teaching or if research is more your thing. If you taught at a state school or small school you probably would still get a great variety of students who take Chem101.</p>