Welcome to our first experiment! This is an old standby of mine; I first did it when I was teaching Comprehensive Science at Newark's Arts High School right after I graduated from college. It was at the beginning of the year and we were talking about the phases of matter. I wanted something to capture their interest (and messy things tend to do that!) and also where we could discuss some of the basic principles of science investigation. (At that point, I didn't have any textbooks so I was flying a bit by the seat of my pants, but that's another story.) The kids loved it; the janitorial staff, not so much (although I tried to make it up to them later with baked goods).
So, yes, this experiment is messy, very messy. There are a few ways to modify it so that the mess is limited but just be forewarned. And, as always, emphasize to your kids that nothing in the experiment should be eaten! (In this one, these are all basic kitchen items, but uncooked rice is not a fun thing for little tummies.)
- 1/4 cup cornstarch
- 3+ tablespoons water
- food coloring (optional)
- plastic sandwich bag (optional, this is one of the ways to reduce the mess level!)
- plastic cups (I bought a sleeve of cups at the grocery store that I plan to wash and reuse for other experiments but you could also use your regular kitchen cups or bowls, although it is a bit better if they all look the same)
- a variety of solid and liquid kitchen items (I chose three liquids (grape juice, water and oil) and three solids (sugar, beans and rice))
- science journal
I divided this activity into three sections, and with the time required to record information in their journals, it took the girls about an hour to do. If you don't want to spend that long, you could divide it over a couple of days or omit the journal component.
Part I - Solids and Liquids
Talk to them about the qualities of solids and liquids and see if they can give you other examples of solids and liquids. For older kids, you can also discuss the third state of matter, gas. (Helium balloons are good examples to bring up for a gas.)
Another thing that can be done during this stage is to talk about inferences, or guesses, that they are making. This is one of the reasons that I chose sugar as one of my solids. The girls automatically guessed that it was sugar (alas, we are a family of sweet tooths) but I made the point that it didn't have to be and opened the pantry, took out the canister of salt and poured that into another cup so they could see how similar it was to sugar. We talked about how else we could tell it was sugar vs. salt and, of course, taste came up (which I wouldn't let them do this time) but also the other senses. Interestingly, salt and sugar look very similar to the eye, but under the microscope one can see that salt tends to form geometric cubes while sugar has a more hexagonal shape. (This website has some great pictures of this, as well as lots of other interesting things both within the realm of science and without.)
(In our case, I wrote all the words for my little one. My older one wrote the titles at the bottom of the first one (oops) but I helped her label her pictures.)
Part II - Mixtures
One interesting thing that developed with our mixtures is that we were able to talk about the idea of dissolving because the girls mixed sugar with water and also beans with water. The sugar dissolved into the water, leaving the mixture still relatively clear (think: simple syrup) in contrast to the beans sitting at the bottom of the cup of water.
Again, allow time at the end to record what happened in the science journal.
Part III: Oobleck
Again, give the child time to draw in their journals at the end of this part of the activity. As this is the real experiment for this activity, it is good to have them record their guess as to whether its a solid or a liquid as well. (Both my girls thought that it was a liquid.)
So, the answer to whether its a solid or a liquid? It's both! Oobleck is actually a mixture. It is considered a colloid, which is a liquid with solid particles floating in it. Another example of a colloid is paint. Oobleck is also interesting because it demonstrates the principles of a non-Newtonian fluid - solid when force is applied to it with the ability of a liquid to flow without the force. I've read somewhere that if you make a big enough batch, you could walk on it! (I'm adventurous but that is a little much even for me...)
Science Process Skills Used In This Activity:
Science Process Skills Used In This Activity:
|X ||X ||X ||X |
Visit the science process skills page for more information on the different skills. I hope you enjoy this activity! If you try it, please leave me a comment to let me know how it goes!