Continuing my blogging project for 2011 where I do a science experiment per week with my six (soon to be seven) year old daughter.
This week’s experiment returned to the world of air pressure and was actually conducted right after experiment #2 from last week. Sam wanted to do another, and who was I to say no? Equipment for this week consisted of…
- A 2-liter soda bottle (empty) and cap
- Some hot water
- Some ice water
- A large pan full of ice
We started by having Sam fill the bottle with the hot water and putting the cap on after a few seconds. We used a funnel, but there was still mess. I think she makes the mess on purpose, but you know what? That’s okay. Nobody ever did science without making a mess and/or killing a bunch of graduate students.
She then lay the bottle down in the pan of ice and slowly poured the ice water over it. Again, more spillage. I think I should invest in some proper science-ey beakers so that we at least look the part.
We then sat back and watched, which for Sam was probably the most grueling part. Soon, though, the plastic bottle began to crinkle and pop as the cooling air inside began to contract and thus lower the air pressure. Sam thought this wanton deformation of grocery items was exciting, so I explained to her about how gasses expand when they get hot and contract when they cool. I tried telling her about the three-way relationship between volume, pressure, and temperature, but she was too busy poking the bottle and asking (perhaps hopefully) if it would explode.
This being a pretty simple experiment, I asked Sam to focus in her journal on describing what we did. I told her that this is an important part of doing science, since one of the qualities of a good experiment is that it can be copied and repeated by other people. Here’s what she wrote:
Experiment 3 Crush with air. We pot hot water in a bol. Pot the led on. The dottle felt hot. We pot it in ice it crushed. The air crushed it.
Next week: we grow stalactites and learn about the importance of careful measurement! Maybe. If that doesn’t work out, we’ll crush something else.