ACARA v9 CONTENT DESCRIPTION “compare the observable properties of soils, rocks and minerals and investigate why they are important Earth resources”
Builds on earlier sorting of everyday materials by how they look and feel. Here that idea is turned on the ground beneath our feet: the soils, rocks and minerals that make up the land and that people dig up and use every day.
Look closely and compare
Scientists get to know a material by its observable properties, the things they can see or feel. A rock has a colour, a hardness, a texture and a shine. By testing the same properties on different samples, we can line them up and compare them, which is how we tell a rock from a mineral, and both of those from soil.
Test a rock
An observable property is something you can see or feel. Tap each test to observe one property of this rock.
Scientists describe a rock by its properties. Pick a test to begin.
Rocks and minerals are not the same
A mineral is one pure substance, often with a regular crystal shape, like quartz or gold. A rock is usually made of several minerals stuck together, like the speckled grey granite. Putting samples in a table makes the differences easy to see at a glance.
Compare three samples
Tap each sample to fill in its row, then read down the columns to compare them.
Sample
Colour
Hardness
Shine
Granite (rock)
?
?
?
Quartz (mineral)
?
?
?
Chalk (rock)
?
?
?
Comparing means lining up the same properties side by side. Fill every row to compare all three.
Soil is a mixture
Soil is different again. It is not a single rock but a mixture: tiny bits of broken rock, sand and clay, all blended with old, rotted plant matter called humus. The plant matter is what makes good soil dark, soft and able to grow plants.
What is soil made of?
Soil is a mixture. Toggle each part on or off to see what builds up a handful of soil.
Soil is not one thing. It is a mixture of broken rock, sand, clay and old plant matter called humus. The plant matter is what makes soil dark and good for growing.
Soil, rock or mineral?
Once you know the differences you can sort samples. A loose, crumbly handful with plant matter is soil. A solid lump made of several minerals is a rock. A single pure substance with a regular shape is a mineral. Practising the sort makes the boundaries clear.
Sort the samples
Decide whether each sample is soil, a rock or a mineral, then tap its bin.
A pinch of dark garden dirt
Sample 1 of 5. Is it soil, a rock or a mineral?
Why they matter
Soils, rocks and minerals are Earth resources: materials we take from the ground and put to use. Rock builds strong walls, clay is baked into bricks, sand is melted into glass, and soil grows almost all of our food. Knowing their properties helps us pick the right material for each job.
Why they matter: match the use
These are Earth resources, materials we dig up and use. Tap a resource, then tap the job it does.
Resource
Use
Choose a resource first, then find the job it does.
Quick self-check
1. An observable property of a rock is one you can: