Here's a new entry to the ExploratoRio Science Snackbook, my homage to the Exploratorium's Science Snackbook.
Overcoming Resistance: Stretch the chain to see the light
The demo is simple and easy to arrange. And it links nicely to the nature of electrical resistance.
You connect a series circuit with a battery, bulb, and light-weight chain. When the chain is relaxed, the bulb lights dimly if at all. When the chain is stretched under tension, the bulb lights more brightly.
The snack write-up may undergo tweaks in the future. Suggestions are always welcome!
Bonus question. Suppose the chain were connected in parallel with the bulb. What difference--if any--would there be in the behavior of the bulb when the chain is stretched?
ETA: I'm such a slow-poke. Don Rathjen already wrote this thing up! With better pictures and details, too!