The molecules in air (and in all gases) are constantly moving, but the amount of movement depends on temperature. At higher temperatures, molecules are more active. They bounce off one another and off the sides of a container with more energy. At lower temperatures, molecules move less and bounce with less energy. A given number of gas molecules will take up more space when warm (because of more energetic “bouncing”) than the same number of molecules at a lower temperature. These characteristics account for much of the air movement that we can observe, both indoors and outdoors. Air currents develop when there are differences in temperatures, because higher-energy (“bouncier”) warm air molecules rise and lower-energy cool air molecules sink.
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 http://www.bioedonline.org/lessons-and-more/teacher-guides/air/
1. Challenge your students to predict whether warm air and cold air behave differently. Ask, Do you think air will sink or rise if it is warmed? Write students’ predictions on the board or have each group make its own prediction.
Keywords: air currents | air molecules | gas | gases | oxygen | properties of air | temperature | water | air
- Moreno, N., Tharp, B., and Dresden, J. (2011) The Science of Air Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-74-3
- Photo © Amanaimages Inc. Licensed for use.
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Funded by the following grant(s)
My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education