I don't have "students" but most of you know I do a lot of work with kids. One of my sitting charges gave me this gem last week:
F: CG, how do you get your nails like that without growing a potato garden?
Me: Huh?
F: Mommy says that if nails get long enough, you'll end up with enough dirt under them to grow a potato garden. You're nails are long and pretty but where are your potatoes?
My nails are about a quarter-inch long which must be a mile long when you're 7.

When I said I wash under my nails every time I wash my hands, she looked at me like I'd just told her the secret of the year.