Friday, June 12, 2015

Kitchen Science: Density Cake

You'll excuse me, I hope, if this reads as a bit scattered today, but I bolted awake this morning to a phone call telling me that Will's chicks were at the post office waiting for us!

The kids and I took a field trip to the fire station a few months ago, and during that trip a firefighter lectured us on the importance of middle-of-the-night fire drills, because when people are awakened from a sound sleep, they awake confused.

Friends, I awoke confused.

I tossed the room looking for my pants, gave up (I found them a bit ago, tangled in the sheets), couldn't find new pants, found pants, forgot where I put my phone down, spent ages looking for it, found it, woke the kids, remembered that the brooder wasn't completely set up, had a right panic about it, couldn't get the heat lamp at exactly the perfect height to emit exactly the perfect temperature and was completely unable to troubleshoot this, tried many things, gave up and went to lie down for a few minutes, remembered the ladder and dragged it in from the garage to serve as a heat lamp stand, couldn't find the address of the post office, set the phone down and lost it again, etc.

Fortunately, by the time the kids had found a height that worked for the heat lamp and got the brooder temperature approximately correct, the fog of sleep had somewhat lifted from my brain (the coffee that I drank as the kids worked was crucial to this process), and I only had to go to the wrong building, call the post office and get directions to the right building, and then go in the wrong doors of the right building once before I successfully located our chicks.

They're safely home now, drinking and eating and bopping around their brooder, and I've declared today a Chick Holiday, because who can be expected to do math and spelling and history when there are FIFTEEN CHICKS BEING CUTE?!?

Therefore, the science project that I'm going to tell you about actually occurred earlier this week. I'd told you that we were finished exploring density for a bit after the Great Density Experiment, but then I realized that the kids had really only explored the density of liquids, so I thought that I'd set up just one last little project so that they could note to themselves that density also applies to solids.

The goal of this experiment is to determine which cake toppings are less dense than cake, and which are more dense. Instead of measuring mass and volume to determine this, the kids let the substances themselves illustrate their density, by placing all toppings on top of the cake, baking it, and then examining it to determine which toppings fall to the bottom of the cake and which toppings stay up top.

To do this experiment, you will need:

  • cake mix. The kids are capable of making cake from scratch, but that's another project in itself, with different variables (Did the kid put in enough baking powder and soda? Did the kid put in the correct amount of flour?), so to make sure that the cake itself would be a neutral substance, I let the kids pick out a boxed cake mix.
  • toppings. Guide the kids just enough to make sure that they're choosing substances that will float and substances that will sink.
  • paper to record the experiment. Lab notebooks would be ideal, but I'm still working the kids up to those.
  1. Have the kids prepare the cake mix and put it in the baking pan.
  2. Lay out all possible toppings. The kids used frozen tart cherries, candy-melt wafers, caramels, chocolate chips, almond slivers, pecan pieces, M&Ms, and dehydrated marshmallows.
  3. Have the kids grid out the cake on a piece of paper, and as they place the ingredients, they should record each location on their grid, along with their hypothesis of the substance's behavior during baking. The grid will look like this:

And the cake will look like this!

Pop the cake in the oven and bake it according to package directions. When it's finished, you can evaluate your hypotheses based on observation--

--and core samples:

I was pleased that the kids hadn't correctly predicted the behavior of every single substance, because surprises are fun. And the little girls who came over to play "mud kitchen" with Syd that afternoon quite enjoyed helping us eat our density cake!

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