The student will know practical applications for insulation and be able to tell the insulation properties of a given list of materials.
Time Required for Lesson: 45-60 minutes plus tour
Activity materials for each group:
Insulation means providing a barrier for the flow of energy, in this case heat. Insulation is used, for example, on stoves and ovens, refrigerators, freezers, water heaters, water pipes and other appliances or industrial applications where it is important to reduce heat and energy losses or to prevent heating nearby objects.
Thermal insulation is the practice of surrounding a building or other object, with a material that conducts heat poorly. There is no perfect insulator, but a thin layer of air resists the flow of heat about 15,000 times better than a good metallic conductor of the same thickness. Many good insulators are made of nonmetallic materials filled with tiny air spaces. These air pockets must be small; otherwise movement of the air by convection currents may transport heat across the space. This tends to occur when an air layer becomes thicker than about ¼ inch (0.6 centimeter).
Heat transfer can also occur through radiation in the absence of intervening conducting materials. For example, the sun’s energy is transmitted by radiation through the vacuum of other space. To reduce heating effects from radiation, reflective paints or metallic coatings are used. Thin aluminum foil in building walls can serve as a radiant barrier. In a thermos bottle or a Dewar flask, heat losses are reduced by evacuating, or removing, most of the air from the space between a double-walled enclosure covered with a polished coat of aluminum or silver.
1. Place the various insulating materials at the front of the class.
2. Explain to the class that they will be trying to create the most efficient insulating device.
3. Divide the class into small groups.
4. Explain the lab procedure:
a. Students will be replicating wall insulation between the two cups when one is put inside of the other. The outer cup represents the shell of the building, and the inner cup represents the drywall inside. Students need to fill the gap between both of the cups. Make sure that students understand that nothing can go inside of the small cup and only one layer of one material can go on the outside of the larger cup. Also, make sure that they create a roof that is hinged or can be removed to place the ice inside.
b. They will then place the cup with the frozen ice inside of their insulating device. The cup needs to be able to stand upright.
c. Place the insulating devices outside. Don’t give any specifics on where they can stick it, just a general area. Some kids will place under bushes to get the benefit of the shading from the plant.
d. Go on tour around LaHouse, and leave the cups outside.
e. Drain and measure the melted ice in each group. Have the group with the least melting tell the group what they did, and the strategies they used. Then explain that no group is the losing group, each was able to keep some of their ice frozen. A glass of water with ice in the sun would have melted in the tour time. Have each group then explain what techniques they used.