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Technologies K–10 · Years 5–6

Which wrap keeps a drink warm: testing insulation

Material World (NSW Science and Technology K–6, 2017); Design and Technologies: Knowledge and understanding, Technologies context: Materials and technologies specialisations (ACARA v9)

Practical, model not builtMedium risk

School laboratory, not for home

In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

This site has no interactive model of its own. Where a step or a material names a Concept Studio model, simulation or tool, it has not been built; an external simulation a step names (for example PhET) is not part of this site.

The idea

Warm water cools towards room temperature fastest at first and then more slowly, and insulating materials that trap air slow the cooling, which a simple cooling model with one number per material describes.

Safety card

Medium riskA teacher supervises

Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

Hazards

  • Scalds from hot water
  • Spills near electrical equipment

Controls

  • An adult prepares and pours water no hotter than 50 °C; cups sit on a tray
  • Thermometers and the kettle kept away from spills; spills wiped at once

Note

Heat is involved: record the activity on Primary School RiskAssess (riskassess.com.au) and follow the school's hot water procedure.

What you need

  • 5 identical 250 mL plastic cups with card lids
  • Wraps: bubble wrap, a wool sock, aluminium foil, newspaper, and none (each wrap used as 2 layers)
  • 5 digital thermometers reading to 0.1 °C (or one probe moved quickly between cups)
  • Warm water at about 50 °C prepared by an adult by mixing kettle and cold water; 1 L measuring jug
  • Timer; spreadsheet

How to do it

  1. Wrap 4 cups, each in a different material of 2 layers, and leave one bare. Add the same card lid to all 5.
  2. Record the room temperature.
  3. An adult pours 200 mL of the warm water into each cup. Record each start temperature.
  4. Record every cup's temperature every 5 minutes for 40 minutes.
  5. Graph temperature against time for all 5 cups on one chart.
  6. With the teacher, find each cup's cooling number k from its start and 20-minute readings, use it to predict the 40-minute reading, and compare with the measurement. Rank the wraps and choose one for a lunch bag.

What you should see

Every cup cools towards room temperature, quickly at first and then more slowly. The bare cup cools fastest; bubble wrap and wool, which trap air, cool slowest. For a cup that starts at 50.0 °C in a 22.0 °C room and reads 40.0 °C at 20 minutes, k = 0.0221 per minute, which predicts 33.6 °C at 40 minutes and 29.4 °C at 60 minutes: the gap to room temperature halves every 31.4 minutes. The learner knows it worked when the ranking repeats in a second trial and the model's 40-minute prediction is close to the measured reading; a large gap points to evaporation through a loose lid or a thermometer touching the cup wall.

What changes

What you change
the wrapping material
What you measure
water temperature over 40 minutes
What you keep the same
  • the same cups and lids
  • 200 mL of water
  • the same start temperature
  • the same room
  • 2 layers of each wrap

Common misconceptions

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

  • Insulation makes things warm (it slows the flow of heat; it adds none).
  • Foil keeps drinks hot because it is shiny (a single layer of foil changes little; trapped air does more).
  • Temperature drops by the same amount every 5 minutes (it drops fastest when the gap to room temperature is largest).

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), NESA. The syllabus taught in 2026; the 2024 syllabus replaces it from 2027. Code read from the official syllabus document (DOCX) on 2026-09-22.ST3-7MW-TST3-2DP-T
  • Science and Technology K–6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.ST3-DDT-01
  • Australian Curriculum v9AC9TDE6K05AC9TDE6P01

Sources

The pages the author read to write this activity.

  1. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
  2. curriculum.nsw.edu.au/learning-areas/science/science-and-technology-k-6-2024/outcomes
  3. primaryconnections.org.au/teaching-sequences/year-4/packaging-pioneers/lesson-4-keep-it-cool

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