In this activity, students can learn one of the principles involved in flight with a strip of paper and their breath.

Bernoulli’s Principle states: as the speed of air increases, the pressure decreases.

This principle is partially responsible for the ability of an airplane to lift off the ground. When an airplane moves through the air, the wings push against the air, so that the airflow is slower under the wing than above it.

As a result, Bernoulli’s principle tells us that there will be more pressure on the bottom of the wing than on the top. The slow, high pressure air underneath the wing creates lift.

When you blow fast air over the top of the strip of paper, the air pressure decreases above the paper. The air pressure below the strip is relatively higher; it pushes the paper upward.

### Objectives

• Describe the characteristics of air.

• Explain how air pressure works.

• Discuss how air pressure affects our daily lives.

• Explain how differences in air pressure create lift.

### Materials

• paper

• drawing or collage materials

### Key Questions

• Draw a model of the experiment.
• Based on Bernoulli’s principle, where are the high-pressure and low-pressure zones around the paper when you blow across the top?
• Based on your answers, why does the paper lift when you blow across it?

### What To Do

1. Give each student a piece of paper.
2. The students hold their paper just under their lips by pinching the short side of the paper between their middle and index fingers.
3. Challenge the students to blow across the top of it and get the paper to move down. The piece of paper will lift up.
4. If the students cannot see the lift clearly, tell them to curl the paper downward slightly and then blow vigorously over the top.

​Teacher Tip: Hold the paper strip with both hands and then blow lightly but steadily. Blowing quickly or strongly will make paper flap.

### Extensions

• What happens if you blow below the paper?
• Predict what will happen if you change the shape of the paper.
• Make a paper airplane designed to demonstrate the Bernoulli effect.

### Other Resources

Kids Science | Paper Airplanes

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