For our science lab, we began by reading about tornado chasers and severe weather, and learned about the history of meteorology. We learned about how weather scientists learn about weather in the past, from tree rings, old diaries, and Antarctic ice, which is filled with ancient air bubbles. We learned some weather folklore sayings, and guessed whether they had any basis in science or not. Then we moved on to learn about science in the water.
We learned about ocean engineers, who study the movements of fish to make better submarines. That led us to our lab, to learn how submarines work by experimenting with pop bottles.
This is what happens to a bottle filled to the brim with cold water in a basin of cold water. It sinks to the bottom.
But, you can pump some water out of your submarine by blowing in air:
Then it floats just below the surface of the water. Up periscope! (The same thing happens when you fill the bottle with hot water, incidentally.)
But an empty bottle cannot be made to sink even part of the way. No matter how much you push on it:
Here are Floppy’s lab notes, which ran for two pages:
