The ingredients for this were:
- Cornstarch
- Water
- Bowl
- Something to mix with
- The space to make a mess
We talked a little bit about solids and liquids before we started. My three year old was able to easily understand that water was a liquid and cornstarch was a solid. We didn't get to complex with matter though. We explained that liquids don't have a certain shape, and they flow. We tipped our measure glass back and forth and watched the water move. We talked about how solids have their own shape, and are hard when we touch them. Then we poured some cornstarch in the bowl and touched it. We spent a few minutes having Isabel identify other solids (her blocks, and her cat...well, close enough anyways) and liquids (her bubble bath and apple juice).
We poured some cornstarch in, and added a bit of water. Isabel stirred it until it was too stiff for her to stir, so I took over. I mixed it until it was thoroughly mixed. Then we talked about solids and liquids again. We poked and prodded the cornstarch water mix. We talked about how it felt solid when we touched it. We even squeezed it in our hands, and watched it go from solid to dripping.
At this point, she asked what would happen if we poured more water in, so I told her to go ahead and pour more water into the bowl. She mixed it up, and was less than thrilled to see that the cornstarch suspension seemed to have lost it's magical half solid, half liquid properties, and was now all liquid.
Her papa's explanation of how the molecules are no longer lining up when she touches it, and that's why its not firm anymore did not help her. So this is where it gets interesting. Isabel turned and asked, 'Mama? How can we make it feel hard again?' I figured this was a great time for the scientific method, and so off we went on our adventure. Here is the simple version of the scientific method we use with our little lady.
Isabel has asked the question - how to make it firm again, and sort of did the research backwards (prior to asking the question.) We reviewed what we had learned already about the suspension of cornstarch and water. We talked about how each had felt separately, and how they felt when we mixed them. Isabel described what it felt like to poke, and to squeeze after we had mixed the two, and the again stated her dismay at the cornstarch turning all liquid when she added more water. Her next step was to come up with a hypothesis - a proposed solution, and then to test that idea. Her hypothesis was to squeeze the mixture. This was a pretty good idea, since with the first round, when it is squeezed, it becomes firm. We were proud of her for thinking of it. She dug her hand in, and squeezed.
No dice. She was not impressed when it ran out of her hand like water. Her conclusion was that squeezing it was not a successful solution to make it hard again. Though, I think she put it something like, 'well. That didn't work. What now?' So she thought some more. Her next solution (hypothesis) was to pour more of the cornstarch in.
So, we poured some in, and she mixed it up. Then, when it got too stiff for her, I mixed a bit. She tried touching it, and...
Success!
Her second hypothesis was successful and correct.
She was very proud of herself, and so was I (she's my only smallie :) ) and because we were now satisfied with our experiment, we spent the next twenty minutes or so just playing in the mixture.
After we finished playing in the cornstarch water mix, we called in the troops (daddy) to help clean it up. Everyone had a lot of fun, and it was a great hands on learning experience for our little lady.
Enjoy!
~Danielle
~Danielle
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