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

Inquiry-Based Learning

Question: Which pendulum will come to rest more quickly—a lighter pendulum or heavier pendulum?

I tied a string with a washer to the end of a ruler to set-up my pendulum.  I taped the ruler to the edge of a table.  I released the washer and timed the swings until the pendulum came to a stop.  I used three different size washers and repeated my trials three times.  Before starting my investigation, I conducted research on pendulums.  My research indicated that the length of string was more important than how heavy the object.  I still made a prediction that the lighter pendulum would come to rest more quickly.  I sat on the floor with a stopwatch and timed the pendulum until I believed it to be stopped. 

My results surprised me because I thought the times would be fairly similar, but instead there was a vast difference.  My results made question my experiment.  I believe my challenge was in determining the precise moment when the pendulum stopped.  I sat down until I perceived the pendulum motionless, but this observation was very subjective. 

Washer size	Average time to stop
Large	6min 36sec
Medium	5min 31sec
Small	4min 29sec

The set-up of my pendulum worked extremely well.  I students would be able to recreate my pendulum easily.  Timing the pendulum did not work well.  I wonder if any of my students would find a solution to this problem. 

The one modification would be to make this inquiry activity about variables.  I would supply my students with different size washers, different length of string, and various materials to create their pendulum.  This inquiry lesson will help students understand they are only allowed to change one variable at a time.