I was subbing at a school where they told me they needed me the whole day: I'd be a floater during the morning, and then covering a 3rd grade in the PM. When I got there, though, they had to really search to find me something to do. I graded papers. I made photocopies for people. Stuff like that. I just wish, though, that they had just said at the outset that it was a half day. I like this district, so it's really not a big deal if it's only a half day.
I get to my 3rd grade class, and the lesson plans were a little sketchy, so I kind of winged it a little. They were in their literature circles, and had to fill out worksheets based on what they were writing. One of the kids came up to me and asked "What's a metaphor?" I explained that it's like calling someone who is mean "a mean old buzzard." Now, he's not really a buzzard, but you can use that word to describe how mean he is. The kid said "Oh! I get it!" and returned to his seat.
Later that day, the kids had to write an essay about their moms for Mother's Day. The teacher asked me to read their rough copies before they wrote their good copies to make sure they were good. When this same kid came up to me with his rough copy, I noticed that he used a metaphor to describe how he felt about his mother.
And this served as a reminder as to why I do what I do.