when you sing camp songs to the babies in the nursery when you're trying to get them to sleep, and when you teach preschoolers other songs, especially motion ones for their motor skill development (that's how you know you are a preschool teacher when you think of gross and fine motor skills when thinking of songs to sing).
when you are in your science class and looking for a way to light the conveniently strike-anywhere match besides the side of the box. Heck, when you know without trying what definitely won't work and what has some potential.
"I'm always pretty happy when I'm at camp with you!"
