Not really a worm #1:
Second ringworm outbreak of the year = ... adventure? And how does it end up on kids' heads? Checking for ringworm plus lice is too much for one scalp.
Not really a worm #2:
I didn't know what mealworms were until I started teaching. You buy them in bulk at Petco, and they tell you to refrigerate them. But if you don't...duh duh duhn...they go through their whole life cycle and become Darkling Beetles. Which look like roaches.
Last week, I picked up this year's set. Yay.
You put them in a critter cage with some oats and stuff and then watch as the mass of oats slowly and almost imperceptibly moves around and wiggles. If you're lucky and you're the teacher, you get to reach in and pull some out to study. If it's an awesome day, you might even get some molted skin.
I heard a rumor once of a teacher who has a self-generating aquarium full of them. Some in the mealworm stage, some in the gnarly white pupa stage, and some beetles...that look like roaches.