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.
Discuss what is happening:
Your hand is warm. Some materials can take that warmth away better than others. Metal is a good conductor, and can take the warmth from your hand easily, so your hand loses heat 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 room-temperature plastic/wood/cloth. But because plastic/wood/cloth is a poor conductor, the heat energy from your finger is barely transferred to them. Since the motion of molecules in your skin stays about the same, your skin feels normal.
Video of the molecule movement here: http://www.middleschoolchemistry.com/multimedia/chapter2/lesson1#conduct....