Activity

Heat: What materials feel warm and cold?

Summary
Touch different materials and record how warm they feel. Understand why in terms of heat transfer.
Science content
Physics: Heat (3)
Lessons activity is in
Materials
  • classroom with a variety of surfaces to touch, including metals
  • worksheet and pencil for each student
Procedure

Students are instructed to walk around the classroom, and touch different surfaces (e.g. metal, paper, wood, plastic, other objects they find).
Each time they touch a surface, they should count to three and then record how warm it feels. Record on their worksheet (attached below): warm, cold, or in between?
Discuss results as a class. Generally metals will feel colder, and insulators such as plastic and wood, and especially cloths or fur, will feel warmer. BUT without guidance as they touch each object, students will generate a variety of results (see photo).

Discuss what is happening:
Your hand is warm. Some materials can take that warmth away better than others. Metal is a good conductor, and the heat of your hand flows through the metal easily, so your hand loses heat to the metal and feels cooler. Other materials (good insulators such as plastic, wood and cloth) do not take the warmth away very easily, so your hand still feels warm.

Higher level discussion of results in terms of what the molecules are doing:
The molecules in your finger are moving faster than the molecules in the room-temperature materials. Because metal is a good conductor, the heat from your finger is transferred to the molecules in the metal. This decreases the motion of the molecules in your skin and makes your skin feel colder.
The molecules in your finger are moving faster than the molecules in the plastic/wood/cloth. But because plastic/wood/cloth is a poor conductor (a good insulator), the heat energy from your finger is not transferred to them, so your skin stays feeling warm.
Video of the molecule movement here: http://www.middleschoolchemistry.com/multimedia/chapter2/lesson1#conduc….

Notes

Might be better to discuss why metals feel cold and other materials feel warm before students start the activity. Then they will be looking for confirmation, rather than a vague instruction to see how things feel, which can be very subjective, depending on students' hand warmth and the texture of the object they touch.

Grades taught
Gr 2
Gr 3
Teaching site
Champlain Heights Annex
Weir Elementary