The Heat Is On!

In order to investigate the heat retention ability of water with different heat insulating materials, this experiment measured the temperatuere of a cup of water after thirty minutes of insulation.

The following materials were used:

Paper Towel - chosen for its likely non-insualting ability.

Plastic Wrap - chosen for its ability to lock out air.

Craft Fleece - chosen for its air spaces that make it hard for molecule vibrations to move through as a solid surface would.

Aluminum Foil - chosen for its normal heat encapsulating ability which is used in cooking.

Hypothesis: The craft fleece will be the best insulator due to the varied airy spaces and the plastic wrap will be the least isnulating due to its thin solid structure.

The original temperature of one cup of water when placed in a coffee cup measured at 99.9°C.  After thirty minutes the water temperature was measured and the results were surprising.  The paper towel showed to have let the most heat escape with a resulting temperature of 62.6 °C.  The next least insulating material was actually the craft fleece, with a final of 64.3°C of heat remaining in the cup.  Next with 65.0°C, was aluminum foil, which was not very surprising as it is often used in cooking to trap in heat.  The final item which was unexpected was the plastic wrap, maintaining the highest temperature of water at 65.5°C. 

Tiller, Enger, & Ross (2008) explain that “the best insulator is a vacuum, since there are no molecules to pass on the vibrating motion” (p. 86).  In this case, the plastic wrap sunk down into the cup, forming a vacuum, creating the best insulation and keeping in the most heat.  

In order to do this experiment in the classroom, a few things would need to be changed in order to keep safe experimental procedures in place. For instance I would not use glass cups as they are too likely to get broken.  I also would provide other thermometers that are also not breakable, such as the one I used which is meant for cooking purposes.  This thermometer was digital which also allowed for more accurate measurements.  Another change I would make is to start with water that is at a much lower temperature to protect the students from burns.

I think that students could really get engaged in this experiment if they were able to bring the items in from home to use as insulating materials.  I would be excited to see what they think could be great insulators and to see how they actually work.  I also think students could get into this if the measurements were taken more often, such as every 5 minutes rather than after 30.  If students did this, they could create line graphs of the data which would allow them to work on those necessary graphing skills.

To make this relevant for students and their lives, we could discuss how insulation works in their homes, how it costs their families money when heat escapes.   Also, we could discuss how it may affect their hot chocolate, coffee, or hot apple cider, then share those as a class after the experiment was complete.

In the end I think that with some changes this could be a valuable lesson in the classroom.  And it continues to fight the environmental fight that I so highly value teaching our students about.