I've taught most high school subjects (just not French, the high maths, physics and chemistry) in a synchronous (live) environment, and am currently teaching English 10 - 12, Biology 11 & 12 and Science 10 in an asynchronous (it's kind of like correspondance) environment.  Right now, it would be nice to be busier . . .

Knowing how to present material in a compelling way is important, but to do so effectively, knowing the material is crucial.