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Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, and Judith Dresden, MS.

What Is Air?

Air surrounds us, yet we rarely think about its composition or why it is important. It is a mixture of colorless, odorless gases, one of which, oxygen, is necessary for functions within cells. Another gas, carbon dioxide, is produced as waste by most living things and also is required for photosynthesis.

Gas molecules are in constant motion. Because heat makes the movement of gas molecules more pronounced, warm air rises and cool air sinks. Many tiny substances can be suspended in air. Some, such as pollen, dust or smoke, can lead to allergies or asthma  in some people. Other substances in air, such as chemicals, can be toxic to everyone.

Most people think of air pollution as being outdoors. But frequently, pollutants can become more concentrated in indoor environments because of limited fresh air circulation. Fortunately, there are many ways to improve the indoor air quality of homes, schools or offices.

This unit uses indoor air pollution as a unifying, real-world theme to teach students important physical and life science concepts about gases, air and the respiratory system. It also presents important environmental health concepts related to air quality and indoor spaces.

Complete instructions for conducting activities in this slide set, including materials needed, setup instructions, student sheets (in English and in Spanish), answer keys and extensions, can be found in The Science of Air Teacher’s Guide, which is available free-of-charge at


1. Ask students to think about the question, What questions do you have about air? Record students’ questions on a sheet of chart paper to be displayed in the classroom. Allow opportunities for students to answer their own questions as they complete this unit.

2. Have students complete the pre-assessment individually; then collect and save each student’s form. Students will refer back to their pre-assessment answers at the conclusion of this unit.

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932

Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education