Heating & Cooling Changes
Observe and describe that some materials change state when heated or cooled, and measure the temperature at which changes occur in degrees Celsius
What a learner can do afterwards
- Describe melting (solid to liquid) and freezing (liquid to solid) with everyday examples
- State that water freezes at 0°C and boils at 100°C
- Explain that heating adds energy causing particles to move more, leading to state changes
1 · Read
Everything is made of tiny particles, too small to see. When something heats up, its particles move faster. When it cools, they slow down. Enough heating or cooling can change a material from one state to another, like solid to liquid or liquid to gas. This change happens at an exact temperature, measured in degrees Celsius (°C).
Leo leaves an ice cube on the table. Warm air heats the ice, so its particles move faster and spread apart. At 0°C, the ice melts and becomes a puddle of liquid water.
Mia boils water in a kettle to make tea. As she heats it, the water gets hotter and hotter. At 100°C, it starts to boil and turns into steam, which is a gas.
Freezing and melting are opposites, and so are boiling and condensing. Cool steam down and it turns back into liquid water. Cool liquid water down to 0°C and it turns to solid ice.
Heating adds energy so particles move faster, and materials change state at exact temperatures: water freezes at 0°C and boils at 100°C.
2 · Watch
Take it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.