Teaching about the atmosphere? Here are a few ideas for the classroom.
Activities about the atmosphere are particularly well suited for talking about air pressure, since air pressure is essentially the weight of the atmosphere pushing down on us. At the Exploratorium we had a couple of really great activities to get at this idea.
- Feel the pressure. You’ve got 14.7 pounds of air weighing down on every square inch of your body. But you don’t feel that. Why? Because it’s been pushing down on you since the day you were born, and your perception ignores constant sensations. But you can get a feeling of just how much pressure that is by creating an atmosphere bar — a one-inch square steel bar that’s about 5 feet long will exert about 14.7 pounds on that square inch. Paul Doherty at the Exploratorium made such a bar, and I’ve placed it on the palm of my hand. It’s amazingly heavy! This is a real eye-opener. You can see a version of this activity on Paul D.’s website.
- Shrink wrap a kid. If you want to really liven things up, put a student in a garbage bag and use a shop vac to evacuate the air (leave their head out!). This has the effect of making air pressure “feelable” (similar to putting your hand in a bag underwater — see below). This activity (Feeling Pressured) is on Eric Muller’s website.
- The weight of the atmosphere. Another nice activity, that not everyone seems to “get” is Paul D.’s magnetic atmosphere model. Thread a series of donut magnets on a pencil. They repel, so they stay spaced, but the bottom magnets are closer together, due to the weight of the other magnets above it. This is a nice model for why air pressure and density is greater closer to the earth; because of the weight of the air above it. See this activity here.
- Boil water at room temperature. A related activity is to boil water at room temperature due to reduced pressure. This can lead to discussions about why lower pressure relates to lower boiling point, and thus that it takes longer to cook food in the mountains (at higher elevation). See this activity here.
For some great descriptions of the effects of altitude on pressure, you might have students John Krakauer’s description of the final part of the ascent of Everest from Into Thin Air.
You can similarly explore ideas of pressure differences when going underwater (a more familiar situation for most students). You can feel the pressure of water by using a plastic bag over your hand to trigger the sensations of pressure on your hair follicles. We don’t usually feel the weight of water when we put our hand underwater because there is nothing to trigger that sensation. See Paul D.’s activity here. You can also talk about the bends, or deep sea fish exploding when taken to the surface, or show a video of styrofoam cup taken underwater (and crushed). Here’s a teacher’s blog on the subject.
We also did a series of activities on the atmosphere and the greenhouse effect, compiled here. These include:
- Modeling the thickness of the atmosphere with a globe and a piece of plastic
- Making a visual model of the composition of the atmosphere using dyed grains of rice. In a one liter bottle, the carbon dioxide in the atmosphere is only a few grains!
- Make a model of carbon dioxide, to show why it’s such an important greenhouse gas (despite how little of it there is in the atmosphere)
Below is the YouTube video of a portion of our live webcast from the Exploratorium, using the infrared camera to talk about the greenhouse effect.