Why not make a Leyden jar. Really easy to make and tons of fun!
The best Leyden jar (or capacitor) I made was an aluminum pie tray with pen tube stuck to it. It stores electrical charge. Just put it on an old TV and turn the TV on and off. Then touch the pie tray to be shocked. (Harmless)
After teaching that electricity can be stored, point out that "these" (you point to electronic capacitors) do the same thing by storing electricity. And do this experiment with the electronic capacitors: