Year 8 Science · Unit 2 · Lesson 16
Challenge Worksheet
Learning Goals
Design a mini-experiment
A scientist wants to test: "Does the hardness of a metal correlate with its usefulness for structural applications?" Plan an investigation comparing at least three metals (e.g. aluminium, iron, and copper) using the table below.
| What I will change (independent variable) | |
| What I will keep the same (controlled variables, list at least 3) | |
| What I will measure (dependent variable) | |
| My prediction (link hardness to structural usefulness) | |
| How I would know if my prediction is wrong (falsification) | |
| One limitation of this experiment |
Would hardness alone be enough to decide if a metal is suitable for a structural use such as a building frame? Explain your reasoning, naming at least one other property that also matters.
1. A student claims: "The best material for any job is always the most abundant one available." Use two specific property-use examples from this lesson to show why this claim is wrong. For each example, name the element, identify the key property, and explain why abundance alone does not determine which material gets chosen.
2. Helium (He) is used in MRI machines to keep superconducting magnets at extremely low temperatures. Using the property-use reasoning framework, construct a full explanation for this use. Your answer should: (i) state at least two relevant properties of helium, (ii) explain why each property matters for this specific use, and (iii) identify one property that helium must NOT have for this use to be safe.
Wrap Up
In one sentence, what was the main idea of this lesson?