Grade 6 · Science · Unit 3 of 8
Expanding, Shrinking and Freezing Water
Why ice floats and roads need gaps
What your child practises
Most matter expands when heated and contracts when cooled, water expands when it freezes so ice floats, an icy surface insulates lakes, and engineers plan for sidewalks, bridges and roads.
Alberta Curriculum learning outcome: 6M 1.3 · expansion and contraction, water's unusual property and how structures are designed for temperature change
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
Why are sidewalks poured in sections with small gaps?
- To make walking harder
- To save concrete only
- To allow for expansion and contraction as the temperature changes
Show answer
To allow for expansion and contraction as the temperature changes
Hint: Without gaps they could crack.
Question 2
A jar of juice is frozen. Why should you leave space at the top?
- Juice expands as it freezes
- Juice shrinks when frozen
- Ice needs air to breathe
Show answer
Juice expands as it freezes
Hint: Water-based liquids take up more space as ice.
Question 3
Why is one end of a big steel bridge built to slide slightly?
- So the bridge can float
- So the bridge can expand and contract with temperature
- So the beams can be painted
Show answer
So the bridge can expand and contract with temperature
Hint: Steel changes size with the temperature.
Question 4
Why can a balloon shrink when it goes outside on a very cold day?
- Air particles disappear
- The cold air inside contracts
- The balloon runs out of colour
Show answer
The cold air inside contracts
Hint: Cooling makes the particles take up less space.
Question 5
A balloon is warmed in the sun. What happens to the air inside?
- It contracts and the balloon shrinks
- It expands and the balloon gets bigger
- It turns into water
Show answer
It expands and the balloon gets bigger
Hint: Heated gas takes up more space.
Question 6
How does a layer of ice on a lake help fish?
- It heats the water
- It acts like a blanket and keeps the water below from freezing solid
- It feeds the fish
Show answer
It acts like a blanket and keeps the water below from freezing solid
Hint: The ice sheet insulates the water.