Properties of materials
Compare and group different kinds of rocks based on their appearance and simple physical properties such as hardness, texture, and colour
What a learner can do afterwards
- Describe at least three observable properties of rocks: hardness, texture, colour, grain size
- Sort a collection of rocks into groups based on chosen properties
- Compare two rocks and describe how their properties differ
The lesson
Rocks are not all the same. You can compare rocks by looking closely and touching them. Four things to check are hardness, texture, colour, and grain size.
Hardness tells you how easy a rock is to scratch or crumble. Texture tells you if a rock feels rough or smooth. Colour is what you see, like grey, red, or white. Grain size tells you if the tiny bits inside the rock are big or small.
Look at two rocks. Granite feels rough and has big grains you can see, like tiny specks of black, white, and pink. Chalk feels soft and smooth, and it crumbles easily when you scratch it with your fingernail.
To test hardness, try scratching the rock gently with your fingernail. If it leaves a mark or crumbles, the rock is soft. If nothing happens, the rock is hard.
Check hardness, texture, colour, and grain size, then sort your rocks into groups.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.