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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.

BC 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.

  1. 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
    Show answer

    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.

  2. Question 2

    Which change turns a liquid into a solid?

    🧊
    • evaporation
    • freezing
    • condensation
    • melting
    Show answer

    freezing

    Hint: Liquid water in a freezer becomes solid ice. That's freezing.

  3. Question 3

    Which two changes need heat to be added?

    🔥
    • condensation and deposition
    • melting and evaporation
    • freezing and deposition
    • freezing and condensation
    Show answer

    melting and evaporation

    Hint: Adding heat makes particles move faster: solids melt into liquids, and liquids evaporate into gases.

  4. 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
    Show answer

    🔥 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.

  5. Question 5

    At what temperature does pure water freeze?

    🌡️
    • 100 °C
    • 50 °C
    • 25 °C
    • 0 °C
    Show answer

    0 °C

    Hint: Water freezes at 0 degrees Celsius and boils at 100 degrees Celsius.

  6. 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
    Show answer

    solid, liquid and gas

    Hint: Water can be a solid (ice), a liquid (water) or a gas (water vapour).

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