Objective
By the end of this lesson, you will be able to understand and explain the changes of state in matter, such as melting, freezing, and evaporation.
Materials and Prep
- Ice cubes
- A small pot or saucepan
- A stove or hot plate (with adult supervision)
- A glass of water
- A hairdryer
- A whiteboard or paper and markers
No prior knowledge is required for this lesson.
Activities
- Observe and describe: Take an ice cube and describe its properties. What does it look like? How does it feel? Can you see through it?
- Melt and freeze: Place the ice cube in the small pot or saucepan and heat it on the stove or hot plate with adult supervision. Observe what happens as the ice cube melts and turns into water. Then, place the pot with the water in the freezer and observe what happens as it freezes back into ice.
- Evaporation experiment: Pour some water into a glass and leave it out in a safe place. Observe what happens to the water over time. Does it disappear? Where do you think it goes?
- Blow drying: Use a hairdryer to blow hot air onto a wet object, such as a piece of clothing or a wet sponge. Observe what happens to the water on the object. Does it stay wet or does it dry up?
Talking Points
- What is melting? "Melting is when a solid turns into a liquid. For example, when you heat an ice cube, it melts and becomes water."
- What is freezing? "Freezing is the opposite of melting. It is when a liquid turns into a solid. When you put water in the freezer, it freezes and becomes ice."
- What is evaporation? "Evaporation is when a liquid turns into a gas. If you leave a glass of water out for a while, it slowly disappears because the water is turning into an invisible gas called water vapor."
- What is condensation? "Condensation is the opposite of evaporation. It is when a gas turns into a liquid. For example, when water vapor in the air cools down, it turns back into liquid droplets and forms clouds."
- What is happening when you blow dry something? "When you blow hot air onto a wet object, like a wet sponge, the heat from the air makes the water on the sponge evaporate faster, so it dries up more quickly."
- Why do these changes of state happen? "Changes of state happen because of temperature. When you heat something up, its particles move faster and spread out, causing it to change from a solid to a liquid or from a liquid to a gas. When you cool something down, its particles slow down and come closer together, causing it to change from a gas to a liquid or from a liquid to a solid."
- Can you think of any other examples of changes of state? "Other examples of changes of state include boiling water, which is when a liquid turns into a gas rapidly, and sublimation, which is when a solid turns directly into a gas without becoming a liquid first. Can you think of any more examples?"