PK – grade 3 students: While doing this activity, the kids will learn about how our lungs work. When we breathe, there is a muscle in our body that helps our lungs move oxygen in and out of our body. When we breathe in, the muscle gets pushed down and it pulls air into our body. At this grade level, kids know that solids, liquids, and gases have different properties. They also know that machines can be used to apply pushes and pulls (forces) to make things move. Have you ever noticed what happens to a bag of potato chips or a closed, partly empty water bottle when you drive from sea level up to or back from the mountains? A nearly empty water bottle closed in the mountains will get “crushed” as you drive down to sea level near the ocean, and a sealed paper chip bag will start out being able to be flattened but it will expand like a balloon when you take it up to the mountains. When we are at sea level, the air above us all the way up to the clouds and to the top of the atmosphere pushes down on us creating pressure on the water bottle and potato chip bag. When a gas is put under pressure, it takes up less room (volume). Sealing a gas in a nearly empty water bottle in the mountains and driving down to sea level causes an increase in pressure on the bottle and the gas molecules are pushed together so they take up less room (volume). The bottle crushes as a result of the pressure on the bottle from the surrounding air at sea level.
Grade 4 – 6 students: While doing this activity, the kids will learn about how our lungs work. When we breathe, there is a muscle in our body called a diaphragm that helps our lungs move oxygen in and out of our body. When we inhale, our diaphragm gets pushed down and it creates a vacuum effect, pulling air into our body. In the mountains, there is less air above us because we are higher up and the pressure of the air is less. At high elevations, gas in the potato chip bag expands and fills the back like a balloon to the point where the bag feels like it will pop. If we take that same bag back down to sea level from the mountains, it will go back to being loose and a being able to be flattened.
Middle school students: The pump takes air out of the vacuum unit and lowers the pressure in the container. This causes the pressure of the air at sea level to push down on the balloon causing the balloon to inflate within the vacuum chamber. The lower the pressure in the vacuum chamber, the larger the balloon becomes. Therefore, air must enter through the balloon and fill it up to create higher pressure in order to be at equilibrium. In this activity, we will pull air out of a chamber containing a balloon. The air above the balloon now is able to push down on the balloon and the balloon inflates with air. The same thing happens with our lungs. Muscles in our abdomen pull down on our diaphragm lowering the pressure in our lungs and the surrounding air rushes into our lungs; this is how we inhale. The vacuum chamber acts like a machine that provides a “pull” or force on the balloon and allows the balloon to inflate. Once it inflates, we can fill the balloon with rice or sand. Solids like rice and sand do no have the ability to be crushed like a gas can and, as a result, the solid fills the balloon resulting in a stress ball/ juggling ball.