Science Club: Geysers

Our third science club meeting was all about geysers. I showed a short video on the geysers in Yellowstone, then it was time for science to happen.

For this meeting, I did both a demonstration experiment and a group experiment. The demonstration experiment involved 2-liter soda bottles and balloons.  If you place a balloon inside a soda bottle but use it to cover the opening in the bottle, you can inflate the balloon by blowing into the bottle.  That is, you can do it if the bottle has other holes in it. Otherwise, pressure just builds up inside the bottle and has nowhere to escape.  I used four bottles for this project - two of them had holes in them and two did not. I put blue balloons on the hole-y bottles and red ones on the regular bottles, then called four volunteers to the front to try and blow up the balloons. I explained why it worked (or didn't), and suggested to the kids/parents that they could try this experiment at home as well.

Then it was time for our group experiment.  For this experiment, every table needed a pan or container for water, small water bottles for each child, and lots of Alka-Seltzer tablets.  We broke the tablets, put them in the water bottles, and covered the bottles with our hands to build up the pressure. Then we removed our hands and watched the geysers erupt!  It turned out that this experiment works better if you put the lid back on the bottle and/or shake the bottle a bit, and it would definitely have helped to have more Alka-Seltzer tablets.  I had 72 packets, which was enough to give each child one packet, but most of the kids wanted to repeat the experiment.

One thing I did with this experiment, in light of the drought situation here in California, was I asked the children to empty their extra water and used water into buckets I had placed in the front of the room. I did some research and determined that Alka-Seltzer is not harmful to trees, so when we were all done with the experiment, I had a couple of volunteers take the water outside to give the trees a drink. One of the children at science club actually applauded when I mentioned that I would be doing this for the trees.

If I were to do this experiment again, I would double the number of Alka-Seltzer tablets to make sure there was enough for everyone to have a second try.  I would probably also buy extra balloons for kids who wanted to try the 2-liter bottle experiment.

You can access my geyser slides here.