Which Material is the Best Heat Insulator? - Science Experiment

Instructor: Amanda Robb
In this experiment, we'll be testing different materials to find the best heat insulator. Once you're done with the experiment, you'll understand why certain materials hold heat better than others.


Research Question: Which type of material is the best heat insulator?
Age: High school and up
Safety concerns: We'll be using a hair dryer to heat up the materials. These can get very hot when run for a long period of time.
Time: 1 hour
Independent variable: Type of material
Dependent variable: Temperature
Control variables: Time and amount of heat applied, amount of material used.

Imagine coming inside from the dead of winter. As soon as you get in, the frost melts and you're free from the bitter cold. Why isn't your house as cold as the outside? You might be thinking that you have a heater, so of course it stays warm. But heat always moves from where there is more heat to where there is less heat, so the heat in your home ultimately wants to get outside. What keeps it in? The answer is a thermal insulator, or a material that doesn't conduct heat well. If the material resists the movement of heat, the heat stays in your house, keeping you warm.

Today, we're going to test different materials to see which is the best thermal insulator. We'll be using a hair dryer as the source of heat and measuring the temperature on either side of the insulator. You can try any materials you want, but we'll suggest some here: aluminum, cellulose, polyurithane foam, and mineral wool, which can be purchased at hardware stores.


  • Two 1/2'' thick plywood boards about 12'' square.
  • Two large binder clips
  • Aluminum foil
  • Cellulose insulation
  • Polyurithane foam
  • Mineral wood
  • Hair dryer
  • Timer
  • Infrared thermometer with a laser pointer, available at online science retailers
  • Ruler
  • Data table

Material Temperature at 0min 3min 6min 9min 12min 15min


1. First, sandwich the first type of insulation in between the plywood boards. Clip it together with the binder clips. Make sure your clips are big enough so the insulation isn't compressed, but just held in place.

2. Measure the width of the insulation. It will be important that you use the same width of insulation for all the materials.

3. Next, measure the temperature on both sides of the board and record this as your temperature for minute 0.

Safety Tip!! Hair dryers can get hot. Handle the nozzle with care and keep your hands out of the way.

4. Use the hair dryer to heat the opposite side of the board for 3 minutes. Take the temperature of both sides again and record your results. Move the hair dryer around so all parts of the board are evenly heated.

5. Repeat step 4 for all 3 minute intervals.


If you're having trouble securing the boards together, you can also switch to C-clamps, available at hardware and science retailers. If you're not seeing changes in temperature, you can increase the heat setting on the hair dryer, or heat the boards for a longer time period.

Discussion Questions

Which material was the best insulator? Was it the one you predicted?

Why do you think some materials worked better than others as a thermal insulator?

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