Make a simple helicopter
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Cut a piece of thick paper about twice as long as it is wide.  Cartridge paper works well, or thin card.  Sugar paper might be worth a try although I've not used it.

Cut down the middle to about half way down it's length.

Fold the two "rotors" in opposite directions, each to right angles with the "body".

Add a bit of blu-tak (or a couple of paper clips) to weigh down the boroom of the body.

Launch by throwing in the air, or dropping from a high point.

If it's the right time of year you could try comparing the action of this with sycamore "helicopters"