Heat Transfer 

For this week’s investigation, my daughters and I gathered two of their winter hats to determine which one helped the cups to better retain heat.  We discussed how this would be similar to helping them stay warm when it is cold outside.  This investigation focused on conduction, which is heat transferred through direct contact.  However in this investigation, we wanted to prevent heat from transferring from the hot water.  We poured one cup of 40° water into each of the identical cups.  We then placed a knit hat over cup A and the fleece hat over cup B.  While we waited for five minutes, we discussed which hat we felt would help the water to keep its warmth.  We felt that the holes in the knitted hat would allow some heat to escape and that the fleece hat would be the better insulator.  After the five minute wait, we gathered the temperatures of each cup of water and found that the cup covered in fleece had a higher temperature than the cup covered with the knit hat. 

            If I were to repeat the experiment, I would want to investigate the difference between rubber and cloth pot-holders.  I have always use cloth ones, but I am curious if the rubber ones would be better insulators.  As a consumer, this would help me to make a better decision when purchasing them in the future.  I also thought it was an interesting suggestion to test something other than water to determine if they would react similarly.  I would be interested in testing to compare liquids to solids.  As I teach my students about the different states of matter, we learn that the gas molecules move the fastest, and that liquid molecules are faster in liquids solids.  We learn that heat is energy and that in conduction heat is transferred by direct contact.  Therefore, it makes me think that a solid would lose heat faster.

My fourth graders currently focus on heat transfer during the unit, Too Hot to Handle.   In this unit, the students learn about the scientific method as we apply it to an inquiry involving spoons in hot tea.  The students are interested in why the spoon becomes hot and wonder if all spoons become hot in tea.  During the investigation, the students test a plastic spoon, a wooden spoon, and a metal spoon.  They calculate the difference between the original air temperature of each spoon and the mean temperature after the spoons have been placed in the hot water for two minutes.  This investigation helps to prove that metal is a good thermal conductor.    

A fun real-world twist to this would be to have the students design the best insulator.  They could create a new style of hat or cup for coffee.  By doing these investigations, students understand how heat is transferred and that some materials are better thermal insulators and conductors.  Investigations allow our students to “gain a deeper understanding of content through the process of doing” (Ertmer and Simons, 2006, p. 47). 

             

References

Ertmer, P., & Simons, K. (2006). Jumping the PBL implementation hurdle: Supporting the efforts of K–12 teachers. The Interdisciplinary Journal of Problem-Based Learning, 1(1), 40–54. Retrieved from http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1005&context=ijpbl