A thaumatrope is a card with different designs on each side which, when the card is twirled, blend into one. Create one or both of these nature thaumatropes.
1. Cut out a pair of pictures. You can make them square or circular.
2. If you cut out square shapes, glue them both right-side-up on opposite sides of a pencil or straw. Place the pencil between your palms and rub your palms in opposite directions, back and forth.
3. If you cut out circular shapes, place one upside-down behind the other. Then poke a tiny hole on the sides of both papers and tie a string (about 6" each) into each hole. Now twirl the string so it gets cork-screwed. Then alternately relax the pull and tighten the pull on the string so it rotates.
In both cases, you should begin to see both images at the same time!