Sunday, January 30, 2011

The Heat Is On!

In my inquiry, I selected a fifteen centimeter piece of square craft felt, a fifteen centimeter piece of a cotton shirt, a fifteen centimeter piece of aluminum foil, and a fifteen centimeter piece cut from a quart-sized plastic bag as my manipulated variables. I poured eight ounces (240 mL) of boiling water into five identical ceramic mugs. The fifth mug remained uncovered as a control. I then covered each mug with one of the selected materials and secured the materials with rubber bands. After thirty minutes, I uncovered each mug and measured its temperature. I recorded my results on a chart and repeated the experiment two additional times to ensure my results were accurate and reliable. As I analyzed my materials to my hypothesis, I was surprised by what my results revealed. On average, all of the water temperatures were reduced by forty-eight to sixty-nine percent. The aluminum foil that I believed would be the best insulator did not provide the best insulation (see appendix). The results of this experiment were extremely unexpected. The plastic bag conserved heat the most efficiently. This surprised me because I would never think to cover a hot dish with a plastic bag or plastic wrap. I never imagined that it would be a practical insulator. The plastic bag’s water temperature was six degrees higher than the aluminum foil. The unanticipated outcome provides insight regarding heat transfer and insulators.

The insight that I have gained from conducting this lesson is that less dense materials are better insulators (Kurtus, 2006). This explains my results; the plastic bag was definitely the least dense material that I chose. Kurtus justifies this reasoning by explaining that the denser the material, the closer its atoms are together. The closer the atoms are together, the faster the transfer of energy takes place (2006).

When I conduct this inquiry with my students, I will ask them to bring in items from their house. I will give them examples such as cotton cloth, potholders, tissue paper, and towels. I will also provide materials from my classroom such as aluminum foil, napkins, paper plates, books, and plastic bags. I will give the students opportunity to choose from a variety of hot and cold liquids to test. I will provide tea, coffee, hot chocolate, cold soda, cold juice, hot and ice water. I will make this inquiry more relevant to the students’by showing them different travel mugs and discussing the propose and what they are made of.

Reference
Kurtus, R. (2006). Thermal insulation Prevents Heat From escaping. Author. Retrieved January
            26, 2011, from http://www.school-for-champions.com/science/thermal_insulation.htm
Appendix

Type of Material
Trial 1
Trial 2
Trial 3
Average
Felt
32°C
35°C
33°C
33°C
Cotton T-Shirt
39°C
40°C
41°C
40°C
Aluminum Foil
47°C
46°C
46°C
46°C
Plastic Sandwich bag
52°C
52°C
53°C
52°C
Uncovered (Control)
31°C
31°C
31°C
31°C
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3 comments:

  1. Charity PeetzFebruary 2, 2011 at 1:47 PM

    Hollie,

    I love the scientific way you went about this experiment. I too wanted to do a 5th cup for a control, but unfortunately did not have a 5th identical cup.

    Was the plastic sandwich bag made of thick or thin plastic? I found that when I used a similar material, plastic wrap, it actually created a vacuum which is why it let the least amount of heat out.

    There are so many ways that we can take this experiment to learn various aspects such as whether the containes make a difference, or the contents in the cups.

    ~Charity

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  2. mtelemacqueFebruary 2, 2011 at 10:31 PM

    Hollie,

    I am reading your blog and found that I started talking out loudly to myself:)I too used aluminum foil and plastic (a ziploc bag) to cover two of my cups. Like you I thought that the best insulator would have been the aluminum foil but I was most surprised when I realized that the aluminum foil was not even second best at that task. Turns out that the Styrofoam plate that I used was more efficient at the job than the aluminum foil was. The best insulator in my group was the ziploc bag. Who would have ever thought of a ziploc bag as an insulator? I never would have used a ziploc bag for anything but storage before but I may have to revise my way of thinking.

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  3. Scitchr 1986February 4, 2011 at 6:40 PM

    Hollie,

    Well done on the fifth cup as a control! Ingenious! I used a variation of plastic wrap, "bubble wrap," with the "bubbles" face down and not "popped." My results found the "bubble wrap" just as effective as the piece of Styrofoam that was used. The temperatures after thirty minutes for both materials were the same.

    I like the fact you are giving students a choice of the liquid to be tested while simultaneously making a connection to the relevance of using travel mugs.

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