Do you have any idea how hard it is to find a jar of borscht in Vermont?
One of my student's questions last week was what other kinds of physical changes there are (besides what we have already learned about: phase changes and solutions). Apparently borscht is a good suspension to work with because you can strain it and see the various sized particles that are mixed into the liquid. Plus it'd be a great chance to introduce kids to a new food.
Only I couldn't find borscht at any of the local places we shop. So my husband stopped on the way home from work yesterday, walked the aisles of the large-ish grocery store with the manager, and came home empty handed. (Thanks for the effort, honey!)
What to do? Consulting my resource, other common supensions (think purees) include pea soup, tomato sauce, and applesauce. So I defrosted some of last fall's applesauce which is made up of nothing but apples and water, and as dinner heated in the oven I had science time in my kitchen! Applesauce passed the test and came to school with me today.
I posed the question: Is applesauce a solution of apples dissolved in water? Kids used a pre-made template to fill in their hypotheses without any discussion. This, after some deliberation on my part. Often my default is to give a lot of information as we start an investigation, but I purposely didn't this time in order to let the process of inquiry stand on its own. I was expecting many kids to overgeneralize what we have learned about solutions and say yes, applesauce is a solution because it's a liquid. But almost everyone commented on the pulp they've seen in applesauce and thought it was not a solution.
This morning in the shower, I had the a-hah realization that if we strained a sugar solution in the same manner as the applesauce, the sugar water would be the control and we would have something to compare the applesauce straining to. It sometimes concerns me that I am thinking about school in the shower, but I can't tell you how many good ideas have come out of those minutes under the hot water while my brain wakes up.
Next we read over the procedure I had embedded in their template and determined that a chart would be the best way to organize their observations. Then we worked through the steps as a whole group. We strained both liquids through a regular colander, a finer mesh strainer, and finally coffee filters, taking notes as we went.
The last step involved small groups straining the applesauce through the coffee filters. I was absolutely amazed last night to find an almost-clear liquid passing through the coffee filters, completely separate from the various-sized apple particles that are suspended in the sauce. The only problem was that the small groups got messy, squeezed applesauce all over the place, and generally didn't do anything that would allow them to collect useful data.
Because our time was up and I had to end the day. So tomorrow we'll start science by sharing conclusions, and learning what a suspension is.