Let’s Talk About It
This activity allows students to model the composition of air using different colors of popcorn. Students will discover that air contains several different gases, including nitrogen (which makes up 78% of the air we breathe), oxygen (less than 21%), argon (slightly less than 1%), and carbon dioxide (less than 1%).
Begin a class discussion about what happened to the popcorn after it was shaken in the large plastic bag. Ask students, Are the colors of popcorn arranged in a special order in the bag? Students should observe that the colors are mixed randomly. To follow up, ask, Can you think of any other kinds of mixtures? Examples might include fruit salad, a bag of different colored marbles, chocolate chip ice cream, etc. You may want to introduce the term, “homogeneous” to describe a mixture in which the components are distributed evenly.
Next, ask students, What color popcorn do you see the most? Second-most? Finally, ask, What color popcorn do you see the least? Students should notice that white popcorn makes up most of the mixture, and that green popcorn is the least common component.
Tell students that air also is a mixture—one made of different gases—and that the different colors of popcorn in the large bag represent the various gases in air. Ask the students to guess which color of popcorn represents nitrogen molecules (white), oxygen molecules (yellow), argon molecules (red), and carbon dioxide molecules (green). You may wish to use the pie chart on the following slide to help illustrate this concept. Point out that while air is mostly nitrogen, we need the oxygen found in the air to live. We also must exhale excess carbon dioxide from our bodies.
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Funded by the following grant(s)
The Environment as a Context for Opportunities in Schools
Grant Numbers: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education