"What grade should I teach?"
This is a very common question - and I'm sure it could be solved with an in-depth personality study.
If you want a restroom in your classroom, teach kindergarten or 1st grade.
If you want to yell at goofy boys for doing goofy things in the restroom, teach 2nd thru 5th grade.
If you like general weirdness, in the vicinity of a restroom, focus on teaching junior high or middle school students.
If you are interested in discovering why there is smoke coming out of the restroom, focus on high school.