All right, I admit it. This one's a stretch. It's not exactly school-related.
This is a simulated electric candle that I've been working on for some time. You know those cool new fake flicker candles? The little ones are cheap but plain, and the big ones are fairly expensive. And almost all of them run on batteries, which can be expensive and inconvenient. I wanted to make a slightly more lasting and less expensive arrangement - of course using stuff I could easily obtain. The project uses no actual flames and requires no special knowledge or tools.
You could certainly use this as a special effect around Halloween, although you'd need to keep it away from younger children. It would also be very pretty for Christmas or Hanukkah. Older kids, say 12 and up, could make these themselves. It's adaptable to use for other occasions; once you have the base complete you can make new "shades" very easily to match any occasion.
I'm really quite proud of this. However, as it's clearly not an education-oriented sort of project, I'm putting it on Instructables instead of here.