All lessons › Rocks, minerals and soils › Lesson 2
Australian primary science · Year 3 · Lesson 2 of 3
Rock testers
Inquiry question: How can we test the properties of rocks?
Check practical materials
Observing and testing
What students learn
We can compare rocks with simple tests: how they look, how hard they are and whether they soak up water. These properties help us decide what a rock is good for.
Success criteria
- I can do each rock test the same way.
- I can record what I observe.
- I can choose a rock for a job using my results.
Preparation and materials
Before this lesson: Students know rocks have properties such as hard, layered or full of holes (lesson 1).
- Rocks from the school grounds or home, about the size of a matchbox, all different — 39 (3 per pair)
- Steel spoons (or steel paper clips) — 13
- Cups of water with a teaspoon — 13
- Paper towel — 13 sheets
- Paper plates or scrap paper to put rocks on — 13
- Magnifying glasses, if you have them — Optional, up to 13
Teacher setup
- Collect rocks the day before, or ask each student to bring one. Choose rocks that look different. A piece of brick or concrete makes a good made-material comparison.
- Wash muddy rocks and let them dry.
- Number each rock with a marker so pairs can talk about them.
- Print one investigation record per pair.
Safety and adaptations
- Wash hands after handling rocks.
- Don’t throw rocks, hit them with hammers or bang them together: chips can fly into eyes.
- Scratch away from your body and keep fingers clear of the spoon.
- Wipe up water spills so no one slips.
Review your school policies and curriculum requirements before teaching.
How to investigate
The lesson sequence should leave pupils with evidence to interpret, not only an activity to finish.
- Pairs look closely at each rock (with a magnifier if you have one) and describe its colour, grains, crystals, layers or holes.
- Scratch test: drag a fingernail across the rock, then the spoon. Rub the mark to check it is a real scratch.
- Water test: drop 3 drops of water on the rock and watch for 1 minute. Does it soak in or sit on top?
- Record each result.
- Choose the best rock for a garden path and explain why.
Teacher modelling prompt
Model each test on one rock. “Look: I see sparkly bits, so it has crystals. Scratch: I drag my fingernail, then the spoon, once each. I rub the mark with my finger. It rubs off, so it was only a metal streak: no scratch. This rock is hard. Water: I drop 3 drops. It sits on top, so it doesn’t soak up water.” Show how to write each result in the table.
Record and explain evidence
Recording question: How are our rocks different?
| Rock number | What it looks like | Scratch test (fingernail / spoon / no scratch) | Water test (soaks in / sits on top) |
|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Who is thinking like a scientist? What evidence do we have?
Check understanding
What should pupils know? Name two properties you can test on a rock.
Explain with evidence: Your fingernail scratched a rock. Is the rock hard or soft? How do you know?
Apply the idea: A garden path gets rained on every week. Would you use a crumbly rock that soaks up water, or a hard rock that water sits on? Why?
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.