Science and Technology K–6 · Year 3

Which spoon warms first? Heat conduction in metal, wood and plastic

Science understanding: Physical sciences

PracticalLow risk

The idea

Heat energy is conducted along a solid, and metals conduct far better than wood or plastic, which is why a metal spoon in hot water soon feels warm at the handle.

Safety card

Low riskAn adult supervises

Hazards

hot water

Controls

teacher pours
jug on a tray
hands off the jug until it cools

Note

Hot water above 50 degrees Celsius is poured by the teacher. Risk assessment before the lesson using the NSW Department of Education Chemical Safety in Schools package (CSIS 1.7 Risk Assessment) or Primary RiskAssess.

What you need

3 spoons of the same length: stainless steel, wooden and plastic
1 heat-proof jug or beaker, 500 mL
hot water at about 60 degrees Celsius (teacher pours)
butter and 3 small beads (a pea-sized dot of butter sticks each bead to the handle at the same height)
a square of card that covers the jug, with three slots for the spoon handles and a hole for pouring
infrared thermometer if available
timer

How to do it

Stick a bead to each spoon handle with a dot of butter, 2 cm above where the water line will be.
Push the three handles up through the slots in the card and rest the card on the jug, so the spoons stand bowls down in the jug with the beads above the card.
Teacher pours the hot water through the pouring hole to the marked line, about 1 cm below the card. Start the timer.
Record the time when each bead slides off as its butter melts. Stop at 15 minutes.
If an infrared thermometer is available, put a small square of matt masking tape on each handle at bead height (an infrared thermometer misreads shiny metal), read each square every minute instead and graph the three lines.
Rank the three materials as conductors and link the ranking to what the handles of saucepans are made of.

What you should see

The steel spoon's bead is expected to drop; the wooden and plastic beads stay put for the whole 15 minutes. Reference thermal conductivities explain the order: stainless steel about 16 W per metre kelvin, plastic about 0.2, wood about 0.15, so steel conducts heat about 80 times better than the plastic and about 100 times better than the wood. Stainless steel is still the poorest of the common metals (aluminium is about 200), and a thin handle loses heat to the air along its length. A fin calculation for a stainless handle 12 mm by 1.5 mm in still air at 22 degrees Celsius (heat loss 10 to 15 W per square metre kelvin) puts the handle 2 cm above 60 degree water at about 40 to 43 degrees Celsius, and at about 35 to 37 degrees once the water has cooled to 50; at 3 cm it would be only about 34 to 37 degrees in 60 degree water, right at butter's melting range of about 32 to 35 degrees Celsius, which is why the bead sits 2 cm up. The card keeps the warm, moist air rising from the jug off the beads; without it, water condensing on the cool wooden and plastic handles could soften their butter too. A dropped bead means the handle passed butter's melting range.

What changes

What you change: spoon material
What you measure: time for the bead to drop
What you keep the same: spoon length
bead height
butter amount
water temperature
card over the jug

Common misconceptions

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

Metal is cold, so it cannot carry heat (metal feels cold because it conducts heat away from the hand quickly).
Wood warms up eventually just as much; it is only slower (in 15 minutes the wooden handle stays near room temperature).

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 2026ST2-8PW-ST ST2-7MW-T ST2-1WS-S
Science and Technology K-6 Syllabus (2024), implemented from 2027; NESA's timeline is 2026 plan and prepare and 2027 start teaching, and schools may choose to implement it during 2026; code read from the outcomes page on 22 September 2026ST2-PQU-01
Australian Curriculum v9AC9S3U03AC9S3H02AC9S3I02AC9S3I03

Sources

The pages the author read to write this activity.

All Concept Studio activities