Year 9 Science · Unit 3 · Lesson 8

Conduction, Convection and Radiation

Challenge Worksheet

Name

Date

Class

Learning Goals

Evaluate a claim about a thermos flask using all three heat transfer methods
Identify which method the thermos is most and least effective at blocking
Use scientific evidence to assess whether a claim is fully, partly, or not at all accurate

Go Deeper

Evaluate the claim

Someone claims...

"A thermos flask blocks all heat transfer, so a drink inside will stay at exactly the same temperature forever. Scientists who designed the thermos eliminated conduction, convection, and radiation completely. The drink is in a perfect thermal bubble, nothing can get in or out. This is why thermos flasks are used in polar expeditions and by astronauts in space."

(a) What part of this claim is supported by the science you have learned about heat transfer? Describe which heat transfer method(s) the thermos genuinely does reduce, and how.

Challenge 3 marks

(b) What is misleading or physically impossible about this claim? Identify at least two specific problems, and explain which heat transfer method the thermos is least effective at blocking and why.

Challenge 3 marks

(c) What additional information or evidence would you need to determine whether a specific thermos brand's performance claim ("keeps drinks hot for 24 hours") is scientifically reliable?

Challenge 2 marks

Show What You Know

1. Australian homes built to 7-star NatHERS rating use a combination of strategies to minimise heat transfer. Design a wall system for an extreme-climate house near Alice Springs that addresses all three heat transfer methods. Name the material or design feature used for each method and explain how it works at the particle or wave level.

Challenge 4 marks

2. A dark-coloured car parked in the sun in Darwin will heat up faster than an identical white car. Use what you know about radiation, specifically absorption and emission of infrared, to explain why, and predict what happens to both cars' interiors at night when outside temperatures drop.

Challenge 3 marks

Wrap Up

In one sentence, what was the main idea of this lesson?