No-Blow Balloon Inflation - Jess Herr

Author

Jessica Herr

Principle(s) Illustrated

1. Air pressure

2. Mechanisms of breathing

3. Muscle contraction

Standards

• HS-LS1-2. Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.

• HS-LS1-3. Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.

Questioning Script

Materials

2 helium balloons

1 clear plastic cup with a small hole drilled in the bottom of the cup

1 drinking straw

Duct tape and/or clay

Procedure

1. Make the hole in the bottom of the cup large enough to place the straw through the hole. Place the straw through the hole so that the straw extends about an inch into the cup.

2. Take one balloon and attach it to the end of the straw inside the cup. Tape the balloon to the straw so that air can only pass through the top end of the straw into the balloon.

3. Take the other balloon and cut off the bottom part (the open end), leaving you with only the top of the balloon.

4. Stretch the balloon to fit it over the open end of the plastic cup. Use duct tape (or rubber band) to secure the edge of the balloon to the side of the cup.

5. You have completed your model of a lung!

Prior knowledge & experience:

Students generally know that the lungs inflate when breathing in, but very few students understand the role of the diaphragm in respiration.

Students are already familiar with the properties of a balloon and how to blow it up.

Root question:

1. Which parts of the model lung represent the lungs, chest cavity, rib cage, and diaphragm?

2. Pinch and pull the diaphragm (bottom balloon) down (away from the lung). Watch the balloon inside the bottle. What do you observe?

3. Why do you think this happens?

4. Do you think this demonstrates inhaling or exhaling? Explain.

5. Push the diaphragm (bottom balloon) up (towards from the lung). Watch the balloon inside the bottle. What do you observe?

6. Why do you think this happens?

7. Do you think this demonstrates inhaling or exhaling? Explain.

8. While pushing and pulling on the diaphragm, hold the opening of the bottle near your face. What do you feel?

9. What do you think would happen if the chest cavity was punctured?

Target response:

Student responses should reflect understanding of breathing and the role of the diaphragm. Students should also explain how air pressure plays an important part in respiration. Using this model provides an example of how air pressure relates to our lungs.

Common Misconceptions:

When blowing up a balloon, we move air into a compressed space, as the balloon inflates. When the balloon is placed inside a sealed bottle, there is no way for the bottle's air to escape, so the balloon does not inflate. The pressure inside the bottle is greater than the pressure that occurs from blowing on the balloon. When there is a hole at the bottom of the bottle, the air can escape; hence the balloon inflates.

Additional Resources/References

Balloon Air Pressure Magic (Instructions)