You’re about to play with one of the first methods of underwater breathing developed for scuba divers hundreds of years ago.! Back then, scientists would invert a very large clear, bell-shaped jar over a diver standing on a platform, then lower the whole thing into the water. Everyone thought this was a great idea, until the diver ran out of breathable air…
Materials: 12″ flexible tubing, two clear plastic cups, bathtub
[am4show have=’p8;p9;p93;p30;p57;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Part I: Fill the tub and climb in. Plunge one cup underwater so it fills completely with water. While the cup is underwater, point its mouth downward. Insert one end of the tubing into the cup and blow hard into the other end. The water is forced out of the cup!
Part II: While still in the tub, invert one cup (mouth downwards) and plunge it into the tub so that air gets trapped inside the cup. Place the second cup in the water so it fills with water. Invert the water-filled cup while underwater and position it above the first cup so when you tilt the first cup to release the air bubbles, they get trapped inside the second cup. Here you see that air takes space, because in both variations of this experiment the air forced the water out of the cups.
[/am4show]
You’re right – that’s actually how the first underwater vehicles were made – they were giant inverted bell-shaped domes equipped with window that sat on a platform which was lowered into the water. You only got so much time on one of those, however, so it also limited how far down you could go. You should check out “Exploring the Deep Dark Sea” by Gail Gibbons – it’s a favorite in our home!
Hi Aurora,
My son used this experiment to “breathe underwater” by sucking air back out of the jar, then blowing it gently back in. We discussed why this wouldn’t work for very long!
By the way, I love the videos that go with the experiments. We didn’t have flexible tubing, but as he watched what it was used for, he decided that two flexible-end straws would do the job. It’s great to find these opportunities for problem solving and critical thinking in Science.
Hi Aurora,
I really like this format with the materials list right at the top. It makes it very easy for me (Mom) to look through the shopping list, figure out which items I don’t have then scan through the experiments and figure out which experiment the missing items belongs to. Then I can watch the video or read the description and decide if I want to get the missing item or if I have something else that would do the job. I don’t have to hunt through all the experiments. I hope you’ll start formatting all the experiments in this way. It’s great!
PS. My daughter is having a blast with the experiments. I’m delighted. I love how you encourage the kids to try out and test different ideas. In the past, she would get really frustrated when an experiment didn’t’ work perfectly on the first try. Now she is telling me about the different ways she tries activities and which works better or worse. She’s learning and growing. Thanks.
Dawnette