You will need:
A bendy straw
A really big nail (about as big around as your straw)
A pom pom
Safety goggles
An empty, clean water or soda bottle with its cap
A hammer
A good pair of scissors

Using your scissors, carefully cut off the “funnel” portion at the top of your bottle.

Put on your safety goggles.  Whenever you use a tool, there is a chance that something might get hit wrong, sending something flying right towards your face and eyes. The safety goggles will protect your eyes.

Place the bottle cap on a safe surface for hammering.  You will be punching a hole through the lid so be sure it’s OK to drive a nail into whatever surface the cap is on – outside on the grass or dirt might be best.

Drive the nail right through the center of the cap.  Once it’s through, twist it around to make sure the hole is smooth and round.  Remove the nail.

Poke the short end of your bendy straw through the cap.  If your hole is a bit too small, put the nail back in and wiggle it around some more to make the hole bigger. If your hole is a bit too big, you can try again with a different cap or seal the area around the straw with glue.

Put the pom pom inside your bottle top and blow through the straw.  Why does the pom pom float?  Why do you think it spins?