It's an unfortunate fact that teachers that really enjoy and understand their subjects is a rare treat and most people won't have the chance to encounter one in all subjects till college.

I think there would be a lot of use for teachers to get additional training in whatever field they're teaching so they have a deeper understanding than just what they remember and what's taught by the book. I don't even really blame the teachers so much because they got into the work to teach generally not to teach a specific subject they may get stuck with.