Science and Technology K–6 · Year 3

Freezing water: it takes up more room as ice

Science understanding: Chemical sciences

PracticalLow risk

The idea

Removing heat turns liquid water into solid ice, and unlike most substances water expands when it freezes, which can be measured as a rise of about 9 percent in volume.

What you need

1 clear straight-sided plastic container about 3.6 cm across (not glass, and not a measuring cylinder, which can crack as the ice expands)
100 mL water measured with a cylinder
permanent marker
access to a freezer at about minus 18 degrees Celsius
ruler in millimetres

How to do it

Pour exactly 100 mL of water into the container and mark the water level.
Stand the container upright in the freezer overnight (no lid).
Take it out and mark the top of the ice at once, reading the ice at the container wall where its surface is level rather than in the middle, because water freezing in a narrow container often ends with a dome or a spike in the centre. Measure the height of both marks from the base and note whether the middle stood higher.
Work out the percentage rise in height, which for a straight-sided container equals the percentage rise in volume.
Let it melt and check the water returns to the first mark.
Link the result to why frozen pipes burst and how ice cracks rock (freeze-thaw weathering).

What you should see

The ice surface sits above the water mark, domed in the middle. Computed from densities: 100 mL of water measured at about 20 degrees Celsius (0.9982 g per cubic centimetre) is 99.82 g, and as ice (0.9167 g per cubic centimetre at 0 degrees Celsius) it fills 108.9 mL, a rise of 8.9 percent; ice at freezer temperature is slightly denser, which lowers the measured rise. In a container 3.6 cm across inside (10.2 square centimetres), 100 mL stands 9.8 cm tall and the ice about 10.7 cm, so the whole signal is 0.9 cm and a 3 mm dome or spike in the centre would add 3 percent to a height read there, biasing the result the other way: that is why the ice is measured at the wall and the shape of the top is recorded. After melting the level returns to 100 mL: the change is reversible and mass is unchanged.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Ice is heavier than water (it is less dense, which is why it floats and why the level rises).
The water level rises because more water appeared.
Everything shrinks when it freezes.

Safety card

Low riskLearners carry it out

Hazards

cold surfaces

Controls

handle the frozen container with a cloth

Note

Risk assessment before the lesson using Primary RiskAssess or the school's own template.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science and Technology K-6 Syllabus (2017), current, taught until 2026; code read from the syllabus document on 22 September 2026ST2-6MW-S ST2-1WS-S
Science and Technology K-6 Syllabus (2017), current, taught until 2026; a Stage 2 outcome, because NSW teaches gradual weathering and erosion in Stage 2 ('investigate why the Earth's surface changes over time as a result of natural processes and human activity'), while the Stage 3 surface-change content under ST3-10ES-S covers sudden geological change and extreme weather events, its other content group being Earth's place in our solar system; code read from the syllabus document on 22 September 2026ST2-10ES-S
Australian Curriculum v9AC9S3U04AC9S3I03

Sources

The pages the author read to write this activity.

All Concept Studio activities