Grade 4 · Science · Unit 3 of 6
Phase Changes
Melting, freezing and more
What your child practises
The six changes of state, whether heat is added or taken away, and everyday examples like dew, frost and drying puddles.
Yukon Curriculum learning standard: Phase changes: melting, freezing, evaporation, condensation, sublimation and deposition
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Put the steps of the water cycle in order, starting with the sun.
- ♨️Water evaporates into the air
- 🌧️Rain or snow falls back down
- ☁️Water vapour condenses into clouds
- ☀️The sun heats water in a lake
The sun heats water in a lake → Water evaporates into the air → Water vapour condenses into clouds → Rain or snow falls back down
Hint: The sun's heat makes water evaporate. The vapour cools and condenses into clouds, then falls as rain or snow.
Question 2
Which change turns a liquid into a solid?
🧊- evaporation
- freezing
- condensation
- melting
freezing
Hint: Liquid water in a freezer becomes solid ice. That's freezing.
Question 3
Which two changes need heat to be added?
🔥- condensation and deposition
- melting and evaporation
- freezing and deposition
- freezing and condensation
melting and evaporation
Hint: Adding heat makes particles move faster: solids melt into liquids, and liquids evaporate into gases.
Question 4
Is heat being added or taken away? Tap an item, then tap its basket.
Sort into: 🔥 heat added · ❄️ heat taken away
- 🧈butter melts in a warm pan
- 🕯️melted candle wax hardens
- ☀️a puddle dries up in the sun
- 🌱dew forms on cool grass
- 🪟frost forms on a window
- ♨️water boils in a kettle
🔥 heat added: butter melts in a warm pan, a puddle dries up in the sun, water boils in a kettle · ❄️ heat taken away: melted candle wax hardens, dew forms on cool grass, frost forms on a window
Hint: Melting, evaporation and sublimation need heat added. Freezing, condensation and deposition happen when heat is taken away.
Question 5
At what temperature does pure water freeze?
🌡️- 100 °C
- 50 °C
- 25 °C
- 0 °C
0 °C
Hint: Water freezes at 0 degrees Celsius and boils at 100 degrees Celsius.
Question 6
What are the three common states of matter?
🧪- solid, liquid and gas
- hot, warm and cold
- rock, water and air
- ice, rain and snow
solid, liquid and gas
Hint: Water can be a solid (ice), a liquid (water) or a gas (water vapour).