What is hot? When an object is hot, how is it different from when it is cold?
What happens at the microscopic level when hot and cold objects interact? How can we represent matter, in various states, at the molecular level?
Why do different liquids and solids transfer energy (for example, heat energy) at different rates? Can you freeze air? What is in the bubbles of boiling water?
Students use what they have learned to build their own insulator.