Heat Traveling Through Solids

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Updated on Mar 31, 2014

Grade Level: 6th - 8th; Type: Physical Science


This project looks for a correlation between the ability of selected materials to conduct heat and a material’s density.

The goal is to have the student formulate and test a hypothesis about heat conduction in solid materials.

  • Can a material’s density be used to predict its ability to conduct heat?
  • Do metals conduct heat differently than non-metals?

All materials are made up of atoms or molecules that are in constant motion. As a material is heated, the atomic or molecular vibrations become larger and the temperature increases. When sufficient heat is absorbed by the material, its solid structure breaks down and the material melts.

The best conductors of heat are metals. This is because heated electrons in these materials are free to move around and collide with atoms and other electrons. This causes heat to spread through the material.

Liquid crystals are materials that change color with temperature when viewed under white light. When a liquid crystal indicator sheet is placed in the path of a heat wave traveling from a hot region to a cooler one, color changes occur, reflecting increases in temperature. Each color represents a different temperature.

  • Temperature-sensitive liquid crystal sheet (12-in x 12-in, 25 to 30 deg C sensitivity)
  • Styrofoam cups
  • Water
  • Spray adhesive

Materials can be found on the Internet or at a Wal-Mart-type store.

  1. Read about heat conduction in solids and formulate a hypothesis that predicts whether the ability of a material to conduct heat can be predicted from its density.
  2. Collect sheets of different types of solid materials and tabulate their densities.

Densities for most materials may be found in tables on the Internet. Alternately you can calculate an object’s density by dividing its mass by its volume. Volume can be obtained from water displacement measurements.

  1. Cut each of the samples to be tested into strips about 1 inch wide and about 5 inches long.
  2. Cut a piece of the indicator sheet and attach it midway along the first sample with a spray-on adhesive.
  3. Place one end of the sample in a Styrofoam cup filled with hot water, and the other end in a cup filled with room temperature water. Be careful not wet the liquid crystal sheet.
  4. Measure the time it takes for a color band to move from the hot end of the sample to the cold end. This is a measure of the ability of the material to conduct heat.
  5. Repeat these steps for each of the sampled materials.
  6. Evaluate your hypothesis in view of your data. If necessary revise your hypothesis and conduct additional experiments to test the revision.



Type of material


Liquid crystal transit time

Material 1



Material 2



Material 3

Material 4

Material 5

Terms/Concepts: Atomic vibrations; Heat; Temperature; Thermal conduction; Metals; Insulators; Density; Liquid crystals


Dr. Frost has been preparing curriculum materials for middle and high school students since 1995. After completing graduate work in materials science at the University of Virginia, he held a postdoctoral fellowship in chemistry at Stanford. He is the author of The Globalization of Trade, an introduction to the economics of globalization for young readers.

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