Students conduct experiments to see that air expands when heated and contracts when cooled. They also observe that hot air rises in cooler air. By modeling the expansion and contraction of air particles, they see that warm air is less dense than cold air. They also learn the role of heat energy in the expansion and contraction of gases.

Student Resources

• 2.1 Vocabulary
• 2.2 Expand and Contract
• 2.3 Hot Air Rises
• 2.4 Spiral
• 2.5 Section 2 Assessment

Learn by Reading

For additional content-area reading, check out the Houghton Mifflin Science eBook: Grade 1, Unit F, pages 8–11.