[snarkpup]

Bend firecrackers in half, light the middle, they fizzle but then explode when you stomp on them.
Seeing how high you could make tin cans go by putting firecrackers under them.
Chemistry sets.
In shop class we made magnetizers that ran on 120 volts and a zillion amps, with a strip of tinfoil intended to blow before the fuse did. Incredible fun!

[WorksinKOP]

“Bend firecrackers in half, light the middle, they fizzle but then explode when you stomp on them.” Also blew up if a little piece of fuse had remained.