This is a simple project guaranteed to get children moving. This is not original but I have known how to do this ever since I myself was a small child.
You take a strip of paper about 2cm. wide by 10cm. long. The paper must neither be too stiff, nor too soft, nor too big! (Step 1).
Cut along the continuous lines, as shown by the scissors symbol. One cut along the middle of the strip lengthwise about 2/5ths down, two more cuts slightly higher than midway and each 1/3rd. the width of the strip. (Step 2).
Make folds along the dotted lines, and first bend flaps 1 and 2: one forward and one backward, but both flaps bent upwards (if they point lower than the horizontal, it will not work!). Fold the two lower flaps 3 and 4 over each other. (Step 3).
Twist the lower end of the stem at point "x". (Step 4).
Raise this well above your head and let fall freely. It will straighten itself and glide down, whirling like a helicopter propeller. (Step 5).