Introduction to Scientific Observation: Dancing Raisins
Sweet Pea is 4 years old.
From: I have been looking forward to getting a lab kit for Sweet Pea so I was very excited when I found a Primary Science Set that was suitable for preschoolers. The kit included 10 activity cards and this “Dancing Raisins” activity was one of them. Note that this activity can easily be done without a science set just by using common items from around your kitchen.
Club soda or other clear soda. (I suspect using Champagne could make clean up time a lot more fun for the adult. )
Beaker or other clear container.
Paper and pencil (optional).
Help your tot fill the beaker with soda water and set the raisins on a plate.
Allow your tot to drop the raisins into the beaker and watch what happens.
Keeping in mind that observation is an important part of the scientific method, ask your tot to describe what she sees. Optionally, use the paper and pencil to record your tot’s observations.
If your tot is interested, discuss why the raisins are “dancing”.
So just why are the raisins “dancing”? Carbon dioxide is forced into the soda to make it “carbonated”. The carbon dioxide can easily come back out of the soda and it does so as little bubbles on the raisins. The raisins are more dense than the soda so they immediately sink when dropped into it. However, when enough bubbles of carbon dioxide cling to a raisin, it is lifted to the surface of the soda. As soon as the bubbles reach the surface, the carbon dioxide is released into the air and the raisin (which is no longer held up by the bubbles) sinks back to the bottom. Eventually too much of the carbon dioxide will escape from the soda and there will not be enough left to form on the raisins and raise them to the surface.
Below is a video of the dancing raisins. (If you aren’t able to see it, try reloading the page.)
We had a little trouble with this at first (as described below in the Notes from the Trenches), but once we got going, Sweet Pea was thrilled with this activity. She kept saying, “I love science!” which was exactly the reaction I was hoping for.
This was a wonderfully fun activity for us and I recommend it for preschoolers and up.
I also want give you a quick review of the Primary Science Set that I bought for Sweet Pea. The equipment is made from sturdy and high quality plastic and the pieces are sized correctly for a preschooler’s little hands. In general, I was happy with the set with a few of minor complaints. The first is that the tweezers are impossible to use with the beaker. Sweet Pea tried several times to remove the raisins from the beaker with the tweezers, but they were just too short. When she pushed them into the beaker, she no longer had enough leverage to close them. Secondly, the activity cards never suggest an activity that uses the flask, which was unfortunate because when I asked Sweet Pea what was the first activity she wanted to do, she said, “Something that uses the flask!” Lastly, and this might be overly critical, but it bothered me that all the activities use imperial measurements. The beaker is marked with 1 cup and 1/2 cup measurement lines. Science is almost always done using the metric system and it just seems silly not to introduce children to it immediately.
Notes from the Trenches:
My husband got a Soda Siphon for Christmas but when we tried doing this activity with the soda water it created, the raisins didn’t dance. Apparently there just wasn’t enough carbonation in the water and the raisins just sat on the bottom of the beaker.
I quickly located a can of store bought clear soda in our fridge and we were able to use it for the rest of our activity. However, this little hic-up made me think that it would be fun to turn this activity into a real experiment by using different types of soda (Tonic water, Club Soda, Sprite, 7-up, etc) and counting the number of times the raisins float or sink in a minute.