Summary

In this demonstration, students will learn to appreciate the power of air pressure.

Grade Level

Elementary or middle school

Objectives

By the end of this lesson, students should be able to

• Recognize that air pressure is a rather strong force.

Chemistry Topics

This lesson supports students’ understanding of

• Pressure

Time

Teacher Preparation: 60 minutes

Lesson: 45 minutes

Materials

• Water
• Cup (enough for each student plus one more)
• Playing card or index card
• Straws (enough for each student)
• Plastic bottle with small hole
• Item that fits snugly in small hole
• Empty bucket

Safety

No specific safety guidelines are necessary.

Teacher Notes

• Even some of the adults who saw this demo were impressed.

Demonstration

PART I

Fill a glass with water and cover the top with a card. Turn the glass upside down and show the students that the air pressure holds the card in place.

PART II

Students work with straws in a glass full of water. They place a finger over the opening of the straw that is outside of the water and they lift the straw out of the glass. When they remove their finger, the water races out because of air pressure.

PART III

An old bleach bottle has a hole near bottom and a tiny object such as a pencil fits in the hole. Fill the bottle to the top with water and cover the top with the lid, closing it tightly. Put the bottle over a bucket and remove the pencil. The air pressure holds the water inside of the bottle. When the lid is loosened (not even removed), the air pressure forces the water out through the hole.