Models can be powerful tools when teaching science. They allow students to visualize concepts that can be difficult to picture in their heads.
If you ask students what the most abundant gas in the atmosphere is, their first guess is usually oxygen. And when you say no, their second guess tends to be carbon dioxide. When we talk about the composition of the atmosphere and the effect of greenhouse gases, students may picture the atmosphere being FULL of carbon dioxide... and rightfully so- statistics estimate that 45 billion tons of carbon dioxide are released every year. But how much is that?
I wanted to build a model of the atmosphere so students could see that there isn't very much carbon dioxide in the atmosphere relative to other gases.
I like that it is easy to see how much nitrogen is in the atmosphere compared to oxygen and other gases. So much easier for students to visualize!
I want to point out that whenever you use models in class, you need to discuss with students any limitations the model might have to avoid misconceptions.
Overall, the entire thing only cost me $9 to make and I had enough spheres left over to make another. Pretty cost efficient compared to ordering one from a science supply company!
If you would like to check out other resources I use when teaching about gases in the atmosphere and the biogeochemical cycles, check out this blog post.