Some of our everyday environments are constructed for us as buildings. This project has concentrated on buildings. Other environments have been “built” for us as clothing, appliances for cooking, cars, roadways, and bridges. Our environment is filled with technologies constructed for our convenience and comfort. Heat transfer is involved with how many of these things work. For example, the clothing we wear has been designed and constructed to keep us warm or cool or just plain comfortable throughout the day.
* These pictures will guide the discussion and activity: (http://theselsproject.org/wp-content/uploads/2013/02/heat-transfer-images-copy-2.pdf)
* Optional item:
– Infrared Thermometer
Use the pictures to guide discussion about how heat transfer is involved in our everyday lives. These pictures were borrowed from Energy Sleuth from the Maine Mathematics and Science Alliance: http://www.powersleuth.org/.
For each picture you can ask students to describe the role of conduction, convection, and radiation. In many cases, all three concepts of heat transfer are involved.
A key point for each pictured situation is to describe where the heat comes from and where it goes. Heat is always on the move. Some things slow it down like insulation but others allow it to move easily like a cooking pan.
The picture of the ice cream cone will be interesting to discuss. Instead of looking at a source of heat, like a fire, we are looking at an object that is absorbing heat from the air. Students may want to talk about the ice cream losing “cold” to the air. This may require some open discussion and students offering several, often conflicting, explanations to start a process of rethinking this situation in terms of heat flow.
The person with the scarf offers different kind of challenge. Instead of gaining heat from the air, the scarf slows the heat transfer from the body. Students may want to revisit the [incorrect] idea that the scarf keeps the cold out. Again, getting students to generate and share and critique explanations will be important. But how does it slow heat transfer? Challenge students with this point. The scarf is an insulator by wool being a poor conductor of heat and by trapping air near the skin so that there is no convection to circulate body heat away.
Conduction with connections to radiation and convection<
Next Generation Science Education Standards
Scientific and Engineering Practice:
– Asking questions (for science) and defining problems (for engineering)
– Constructing explanations (for science) and designing solutions (for engineering)
– Systems and system models
– Energy and matter: Flows, cycles, and conservation
– Structure and function
- What is the difference between “heat” and “cold”?
- How do we feel “heat”? How do we feel “cold”?
- Why do some things “feel” cold and some “feel” warmer even though they are the same temperature?
- Think of various kinds of clothing and describe how they function with respect to conduction, convection, and radiation.