Build your own working stethoscope to listen to the 'lub-dub' sound of your heart! You'll learn how sound waves travel through tubes and how a diaphragm helps amplify heartbeats.

Tools

• scissors

Materials

• clear vinyl tubing (approx. 3 feet)
• plastic funnel (1 small)
• balloon (1 standard size)
• Y-connector plastic fitting (1 piece)
• adhesive tape (1 roll)

Safety

• Adult supervision required when using scissors.
• Be careful not to push the tubing too deep into ears to avoid injury.
• Balloons can be a choking hazard for very young children.
• Adult supervision required for sharp objects.

Steps

1. Take your long piece of clear vinyl tubing and fold it in half. Cut directly down the center to create two long strips.
2. Take one of those strips and fold it in half again, then cut it down the center. You should now have one long piece of tubing and two shorter pieces.
3. Insert one end of the long piece of tubing into the narrow end of the funnel. Use adhesive tape to wrap around the joint securely so no air escapes.
4. Take the other end of the long piece of tubing and push it into the bottom stem of the Y-connector.
5. Take the two shorter pieces of tubing and attach one to each of the two open arms of the Y-connector. These will serve as your earpieces.
6. Prepare the diaphragm by cutting the neck (the narrow opening) off the balloon.
7. Stretch the remaining rubber part of the balloon tightly across the wide mouth of the funnel. Ensure it is taut like a drum, then secure it with tape around the rim of the funnel.
8. Place the two short tube ends in your ears and hold the balloon-covered funnel firmly against your chest to listen to your heartbeat!