How Heat Moves
- Physics
- Ages 11–14 · Grades 6–8
- Hands-on experiment
What you’ll find out
- Heat moves by conduction, convection and radiation.
- Only radiation crosses empty space; the other two need material.
- Insulation slows heat down rather than stopping it.
No sign-up and no real names. In the lesson you check your understanding as you read, run the experiment yourself, and practise until it sticks.
Three different routes
Heat always moves from hotter to colder, and it gets there by three different routes. Conduction is heat travelling through a solid: leave a metal spoon in hot soup and the handle grows hot. Convection is heat carried by a moving liquid or gas: warm water rises, cool water sinks and the whole pan stirs itself. Radiation crosses a gap with nothing in it at all, which is how you feel the Sun on your face. The first two need a material to travel through; radiation does not, which is why sunlight can cross empty space.
You can slow it, not stop it
A hot drink in an ordinary mug is cold in minutes; the same drink in a vacuum flask stays hot for hours. The flask is not doing anything magical — it attacks each route separately. A gap with the air pumped out stops conduction and convection, because both need a material to work through. A shiny silver lining reflects radiation back inwards. Yet the drink does cool eventually. Insulation slows heat down; it never stops it. Given long enough, everything reaches the temperature of its surroundings.
Curriculum links: NGSS MS-PS3-3 · NGSS MS-PS3-4