This week's inquiry experiment was fairly simple on paper; fill four identical mugs, pour some hot water into them and cover each with a different insulator found around the house. Leave the covered mugs on the counter for 30 minutes and then measure the temperature change with the thermometer from our science kits.
There was no stipulation as to how hot the water needed to be so I put each mug in the microwave for 2 minutes each, then covered them and left them out. Half an hour later I attempted to measure the temperature and discovered that my little thermometer could only reach 50 degrees Celsius. Sooo....I had to toss that experiment. Unmeasurable= Invalid.
Next, there was a lively debate between my fiance, my fiance's son who is an AP student in science and myself. We went back and forth on whether I should microwave the water or use hot tap water, if I should do all the mugs at once or one at a time and what insulators I should use. That's typical for my house, being surrounded by smart people is lively if not informative.
I decided to do it my way. I usually do. I heated tap water to its hottest, measured one cup of water, put it in the mugs and topped them. I came back half an hour later and checked the temperature. Strange, how on earth could the plastic baggie be the best insulator? Something had to be wrong, I had also used a 1" piece of Styrofoam, a piece of foil and a wash cloth as my insulators. Surely the washcloth or the baggie had to be poor insulators but no, it didn't work that way at all.
So I sighed, and did the experiment once more. It sounded so simple on paper!
This time when I measured the results, the water for the Styrofoam, the baggie and the wash cloth all measured in at 36 degrees Celsius. What was up with the Styrofoam? It ended up that the foil won out with a temperature of 37 degrees Celsius.
I decided to leave my experiment at that. Maybe foil as an insulator was something I could look into later on in my free time. It also occurred to me as I was pondering the results that this experiment had no control and to get truly valid results, I would have included a control.
My conclusion: I wouldn't have my students do an experiment like this having tried it on my own with three widely different results. If I was instructed to have my students do it despite my objections, I would give more specifics; give a starting temperature for the water, and to make sure they used a control.
And now for a question from my professor:
What, specifically, would you like students to learn from this experiment?
To answer that question, I pulled up the Sunshine State Standards for Fifth Grade-
The Nature of Science
Standard 1:
The student uses the scientific processes and habits of
mind to solve problems. (SC.H.1.2)
Standard 2:
The student understands that most natural events occur
in comprehensible, consistent patterns. (SC.H.2.2)
6. knows ways that heat can move from one object
to another.
Did you achieve this goal when you engaged in the experiment?
To be honest, I did not. The experiment shows that insulators work to contain some heat, but does not show where the heat went nor how it escaped the coffee mug.
You raise some valid points about this experiment. I started with having my water all at the same starting temperature and used very different materials. To be able to discuss this with the students, they would have to understand all three ways of heat transfer, especially conduction. The heat was being conducted into the mug and the counter top or the air touching the mug. I think if we could wrap the mugs completely in the materials, this would be a better way of showing the insulating properties of the materials.
ReplyDeleteAlso a valid point Kelly but if the mugs are all the same material and size and they are all sitting on the same counter side by side those variables should be pretty much identical so we should be only testing the conduction, radiation, or convection of the heat through the materials that are covering the mugs. The heat loss through the mugs to the counter tops should be at the same rate for each mug. Making it a pretty reliable test of the materials on top. Now of course that would be in a perfect world and who knows for sure that the mugs are identical and one or two would not lose heat energy faster due to some imperfection or something but over all if they are the same size, shape and material it should be fairly reliable results.I have to admit that I did the test three different times to verify my results and I was quit surprised to find in my test Aluminum foil beat out saran wrap, a cotton washcloth, and newspaper. Not exactly what I had expected but it did win all three times.
ReplyDeleteMark,
ReplyDeleteI had similar results with foil and I was a bit surprised. I know when I am cooking, if I wrap something in foil it will be far less likely to burn or dry out than something that is exposed directly to my oven which uses heat convection to cook food. I must have thought that foil would dissipate the heat, rather than retaining it.
Also, I had to wonder if the experiment would have been more accurate if we had used beakers, rather than coffee mugs. Ceramics are not perfect in overall density, even if I had four apparently identical mugs, they still may have been different in the way they distributed heat throughout the walls of the mugs.