- Two funnels
- Plastic tubing
- A balloon
- Elctrical tape
1. Insert both funnels inside the ends of the tubing. Tape the tubing to the funnels if needed to secure the ends.
2. Cut the balloon and pull it over the end of the funnel and secure it with electrical tape.
Be sure the balloon is pulled tight and flat.
3. Be sure the room is quiet. Place the balloon end over your heart. Listen in the other end. Try running around and getting your heart going faster. Then listen again. What happens?