The two biggest things would be to see if they can take instruction from you, and to see if they can sit like normal people when you give instructions to someone else. And if this is an audition and they don’t look at you like you’re the smartest person in the world, I wouldn’t take them, because it will only get worse.

If your starting a middle school chorus, I’d also suggest that you don’t start with the music you want to perform. Start with rounds and single voice songs. Warm them up to singing on pitch and taking direction, and use starter songs that are easy (like you can teach them in 10 minutes) so you can focus on training them to learn how to learn music.

Don’t chew gum. Chorus teachers don’t like that.