Making Quicksand

Making Quicksand

Non-Newtonian Fluid

I was testing one of my science experiments recently with a visiting grandchild. We were making oobleck, a non-Newtonian fluid characterized by the fact that it has some properties of a solid and some properties of a liquid. Quicksand is a non-Newtonian fluid. I’d made this myself when I had no children visiting, so it would be a good test for my upcoming book, “Can You Bend a Pencil? 10-Minute Science to Delight Your Grandchildren.” First, we read the list of materials and started getting them out.

Grandma: “Yes, we have enough cornstarch. What else does it say we need?”

Grandson: “I’ll get out the bowl. I know where they are. We need a measuring cup.”

As Grandma gets the cup out of a cupboard from a nest of measuring cups, grandson asks: “Will that one hold one cup?”

Grandma: “Yes.”

Grandma watches as grandson measures out a cup of cornstarch and half a cup of water and pours them into the bowl.

Grandson: “Eeeewww. It says mix it up with your hands. You do it, Grandma!”

Grandma mixes the cornstarch and water with her fingers.

Grandma: “Ooooh, look! It drips off your fingers. You can pour it out of the bowl slowly. But, if you push down on it, it’s hard. I wonder what would happen if we got out a hammer and tried to pound it.”

We get out my two small kitchen hammers and pound the quicksand. The hammers make small dents in the quicksand, which quickly disappear as the liquid seems to melt back into a single blob in the bowl.

Grandson: “I bet we could make an island with a rock and float it on the quicksand, and put a palm tree on the island and pour glue on the rock and sprinkle it with pepper to make it look like sand.”

We go outside to find a rock for the island.

Grandson: “There are lots of rocks in the yard, but they’re not big enough for the island.”

Grandma: “There are some larger, flat rocks at the top of the path down to the creek. I use them sometimes to pile up an edge around my garden. We can probably find one there.”

Grandson finds a rock in the woods on the path that is perfect. We go back inside.

Grandson asks if we have cinnamon sticks, celery and whole nutmeg. We do.

Grandson: “Look, Grandma! We can stick the celery leaves in the end of the cinnamon stick. But, don’t you think the nutmeg is too big to be a coconut for that size palm tree/cinnamon stick?”

Grandson: “I know. We can glue two cinnamon sticks together to make a bigger palm tree. Here’s one that’s big enough, but it’s too long. Can you cut it here to make it shorter, Grandma?”

Scissors don’t work, so I take out a large knife to chop off the end of the long cinnamon stick. We get out a bottle of Elmer’s glue, but the top of it breaks off when we open it.

Grandma: “Put a paper towel under the rock in case the glue spills over the side.”

Grandson pours glue from the bottle onto the rock and sprinkles it with pepper to look like sand. Grandma pours the rest of the glue into another glue bottle with an intact top. Grandson glues celery leaves to the end of cinnamon sticks, sticking the celery leaves on them for palm fronds, glues cinnamon sticks together and the nutmeg to the cinnamon sticks. Grandma fastens palm tree together with tape while glue is drying and pours glue from broken glue bottle into another glue bottle. Grandma points out that the glue is not strong enough to hold the palm tree up on top of the rock, so we’re going to pretend it fell and lay it out on the rock, like the trees that fall in our woods.

Then, we put the rock/island on top of the quicksand to watch it float. It slowly starts to sink.

Grandma: “Look, it is slowly sinking. If we put our finger on the quicksand, it feels hard, but if we leave our finger on top of the quicksand, it slowly starts to sink, like the rock.”

Grandson, sticking his finger onto the top of the quicksand/cornstarch and letting it sink slowly down: “This is deep.” By then, we were tired of the cornstarch/quicksand and palm trees. It wasn’t yet 10:00 AM.

 

Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers”

http://newgrandmas.com

Filed in: education • NaBloPoMo Tags: featured • non-Newtonian fluid • oobleck • quicksand