Wednesday, June 20, 2012

Preschool Science: Experiments in Buoyancy

This morning, the girls enjoyed doing some basic science experiments to explore buoyancy: Dancing Raisings, and Egg Floating.  The experiments did not go quite as planned, which gave them an even more important lesson in the scientific process...

The girls love their plastic test tubes (I got a set of 16 test tubes at Oriental Trading a year ago, and they are fabulous for preschool experiments). I opened up a bottle of carbonated water for them and we listened to hear what sound it made when I turned the lid.  Then we observed the bubbles.  The girls filled their test tubes with carbonated water by pouring it through a funnel.  Then I invited them to drop some raisins in and observe.  They sank.  The bubbles collected around the raisins, but they were not sufficient to get them to float.  This is where the girls started learning about the scientific process.  Why were the raisins not floating?  Did we need to use water with more carbonation?  I opened up a different brand of carbonated water, and the raisins still didn't 'dance'.  Maybe the raisins were the problem.  We tried pieces of spaghetti and a bean, and still nothing.  Then I found some Craisins in the pantry.  Finally, the experiment worked!

The Craisins 'danced' by floating to the surface and then sinking down again (the bubbles attached to the Craisins and decreased density allowed for them to float).  The girls watched intently and extended the experiment on their own by poking the Craisins with their fingers and stir sticks and changing the amount of carbonated water in their test tubes. 

They had a good time transferring the water between test tubes by using a medicine dropper as well as pouring it through the funnel.

Next was the Floating Egg experiment.  E put an egg in a glass of water and observed it sinking to the bottom.  Then she helped me add salt, and stirred until the salt dissolved.  She put the egg back in:

The egg still didn't float:

We tried adding more and more salt.  We tried warming the water in the microwave (and the girls noticed that the salt dissolves better in warm water).  Still nothing.  It was good for the kids to see how we ask questions and try different things, even if we never get it to work right.  While the salt and egg were out, we did a bit of egg balancing:

The girls made a lot of wonderful observations, for example when they reached into the water glass they saw that they displaced the water and it spilled.  I threw in some scientific explanations as they were exploring, but what I really want them to take away from the experience is how much fun it is to discover new things about the world around them through experimentation. 

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1 comment:

  1. A lovely collection of experiments and I adore those test tubes!

    Thanks for sharing on Science Sparks


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