For many, many years I have had tea for breakfast, so I know approximately how long it takes for the tea to cool, about 5-10 minutes, so that I am able to drink it. What I was not prepared for was how long it would take for the hot water to cool enough so that I could test it. My testing materials were newspaper (four layers thick), thick leather, heavy-duty wool, and thick cotton. My prediction in efficiency was that the order from the least to most efficient would be: newspaper, cotton, wool, leather. The first mistake that I made was to use boiling water. I tested the mug with the newspaper covering after 15 minutes. It was well above 120 degrees, so I waited until thirty-five minutes had passed; the results were still the same. I then waited until an hour and seven minutes had passed. The water temperature was at or above 120 degrees with the newspaper-covered mug so I decided to wait even longer. After an hour and thirty-seven minutes of waiting, I tested the same mug again. The temperature was at one hundred and twelve. The leather and wool were still at or above one hundred and twenty-two and the thick cotton was at one hundred and fifteen. I decided to do the experiment over this time using hot water not boiling water since I had opened the newspaper-covered mug so many times, which I thought had really skewed the results. This is another reason why teachers should always conduct these types of experiment before they do them in class. You really need to work out the kinks before you do them with the students.
The second round of testing I had much better results. This time I heated the water well but nowhere near boiling. After waiting fifteen minutes I tested the newspaper-covered mug. The temperature was at one hundred and seven degrees, so I decided to wait at least another hour. After waiting one hour and thirty-five minutes I recorded the results again. The newspaper-covered mug water temperature was at ninety degrees, which really shocked me that the temperature had only dropped a mere seventeen degrees over an hour and twenty minutes. I really thought that the temperature would be in the sixty or seventies. The wool-covered mug was at ninety-seven degrees, the leather at ninety-six and a half, and the cotton at ninety-two degrees. They were all really amazing insulators. My prediction was about what I thought it should be, although the wool was slightly better than the leather. Although even more shocking, was that they were all within seven degrees of one another. I thought that the range would be much more spread out, possibly a twenty point spread or even higher.
When I was recording the results for the testing, I thought of what I had read about the Depression. I remember the stories about how people use to put newspaper in their clothes and shoes to keep them warm. After performing this experiment, I can see that the newspaper method probably worked pretty well.
What I learned from doing this experiment is that the students would really be able to learn the concepts of heat flow and enjoy the activity at the same time. Also by doing this type of lesson, the students are not likely to forget the concepts either. Now, I just have to think how I could do more of these types of activities in life science.
