I was just listing one possible chem teacher. Honestly, I'd say that there should be multiple teachers for most of the major classes (except the Arts, budget cuts, you know? Gotta support the foorball team!)
Kobold shop teacher. Most projects involve creating horrible deathtraps.
Pit Fiend teaching Infernal, Balor teaching Abyssal. Due to budget cuts, they both teach in the same classroom. At the same time. Sometimes they teach the same students, as well.
Ettin Assistant Librarian. Learning the Way of Librarianism from GREAT LIBRARIAN TROG.
Aboleth teaching computer classes. The school has recently been mandated to teach the students about how to use computers, and they assigned the teacher from the recently cut Primordial Languages class. Knows even less about dem dere newfangled computrons then the students.