Sunday, February 18, 2018

One of These Dissolves in Water...

Here we have a tale of two Science Clubs.

Thursday's group first checked in on the progress of their upside-down bean plants (which stubbornly refused to grow upside down and instead headed straight for the sun) and their bean plant mazes. All of the baby bean plants are avoiding the twists and turns of their cardboard box mazes and are finding ways to grow straight up as well. I will share photos soon!

We then followed up on last week's yeast experiments by making a super-quick yeasted bread which only required one rise. We could actually do the whole recipe within the two hour time restriction of Science Club. The kids loved watching the yeast bloom, kneading the flour bit by bit into their dough, and seeing it rise until it had doubled in size.

While the bread was rising we read Steve Jenkin's Life on Earth: The Story of Evolution up to the page which ends by saying, "As life forms develop, many plants and animals become larger and more complex. But they do not replace the smaller, simpler forms of life. Today, after 3 1/2 billion years, bacteria -- some of the first living things on the earth -- are still evolving and are among the most numerous and successful forms of life."

Then we began our bacteria experiments. I am working with a scientist at SIU to come up with some experiments for the classroom to help kids better understand the origins of life on Earth. Bacteria is a hard concept... considering that it is invisible... and so we are trying to see if it works to grow bacteria cultures on the kitchen counter in dishes of gelatin instead of agar plates and Petri dishes. If we can find experiments which don't take fancy equipement, more kids will be able to try them and learn from them.

The scientific question was whether bacteria would grow on plain gelatin compared to flavored gelatin (Scott thinks that the sugar in the flavored gelatin might produce a better result... like how yeast grows better when it has sugar... and I think that the food coloring will kill the bacteria outright). First, however, we needed to see if the bacteria will grow on gelatin AT ALL.

So, we took a 9 x 9 casserole dish and I filled it with four packets of plain gelatin plus 2 cups of boiling water plus 2 cups of cold water and let it gel. Then we put a piece of masking tape across the pan, not touching the surface of the gelatin, and left one side alone (the control). Then it was time to add bacteria to the other side and the kids gleefully swabbed a variety of household surfaces with cotton swabs which had first been dipped in a mild saline solution. These surfaces included the floor, the pencils in the communal pencil jar, and the underside of a dirty fingernail.

Last, but not least, we headed outside for some play time on an unseasonably warm day, before coming back in to try out our warm bread fresh from the oven!

Note #1: On Sunday evening, when I'm typing this, the gelatin has equal amounts of splotchy growth on both sides of the masking tape. The side with NO bacteria looks exactly the same as the side WITH bacteria, which tells me that all I am seeing is the gelatin going bad and growing mold. Oh, well. That's Science for you. Now we just have to figure out another plan.

Friday's group is studying Starch, the second of our Carbohydrates in Kitchen Chemistry. The girls began by comparing styrofoam packing peanuts to biodegradable packing peanuts, which are made of starch. Immediately, they noticed the difference in texture and that one is full of static electricity and one is not. Oh, and by the way, one of these dissolves in water...

So they went downstairs to the bathroom sink and ran hot water over the packing peanuts and watched the starch ones shrink into slime before dissolving away. Joyful icky fun.

Next, we popped the balloon inside the remaining balloon string art sculpture from last week. These came out beautifully, by the way, so if you would like instructions for this craft, here are the ones we used. You only need a quarter of the recipe, though, unless you really are making them as decorations for a wedding.

Then it was on to Oobleck (2 parts cornstarch : 1 part water).

Note #2: Be prepared that they will probably play with the Oobleck for almost an hour. There's nothing cooler than a non-Newtonian fluid!!!

When I insisted that it was time to move on, we read about the physics of popcorn, the girls watched a video of popcorn popping in slow motion, and then we popped popcorn. Then they ALSO made tapioca pudding, while I read them page 145 of David Mitchell's book and we did steps 1, 2, and 3 of the "Test for Starch" activity on page 147. He suggests potato, carrot, corn, and turnip and so that is what we used.

Note #3: Don't buy it! Decolorized iodine will NOT work well for this AT ALL.

Next week, we will do the unsalted cracker experiment which David Mitchell suggests in his explanation of Starch on page 145, summarize Starch for our Science Binders, and move on to Cellulose.

Note #4: Don't forget that this book is also available online as a PDF completely free from the Online Waldorf Library.

Note #5: We did tapioca pudding because we had already done a lot with cornstarch, and tapioca is starchy and a natural thickener. However, if you have a child who doesn't like tapioca, here's my favorite recipe for homemade from-scratch chocolate pudding.

    Chocolate Pudding

    In a medium saucepan, combine 1/2 cup sugar, 1/3 cup baking cocoa, and 2 T cornstarch.

    Whisk in 2 cups milk and one egg, lightly beaten.

    Cook and stir over medium heat until mixture comes to a boil.

    Boil for one minute, then remove from heat.

    Flavor to taste with 1/4 tsp vanilla extract and/or 1/4 tsp almond extract. Serve warm.

This post contains affiliate links to the materials I actually use for homeschooling. I hope you find them helpful. Thank you for your support!

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