Hmmm I could go down the list of what's happened in my darkroom this week with the younger kids lol.

forgetting to turn off the focusing switch when loading easels.
Moving the test strip paper/ not holding the blocking board still.
forgetting to use the designated pair of tongs for each chemical.
moving from chemical to chemical way to fast while counting at super speed, some think its smart to count by 2, or 5, or 10s.
Forgetting to flip the negative.
Checking to make sure the negative is placed well before closing the carrier and crushing film.
Taking out a cell phone in the darkroom.

Though not this week, last week somehow a student got a bit of red play dough onto the focusing ring of my nikkor 50mm 1.8 AF lens I bring in to let them use.

Ive learned not to stress about any of this anymore since they are so young. If they mess up we just make another, and use the messed up sheet of paper to paint with or turn it colors in daylight. I think its because of the fact that the city and statewide tests have been over, and they are anticipating summer and dont keep anything else in their minds except that and games lol.