Sorting rocks by their properties

Science · Earth's Systems · ages 7-8

Name ______________________ Date ____________

Which property describes resistance to scratching?
- Colour
- Hardness
- Grain size
Which word describes how rough or smooth a rock feels?
- Texture
- Colour
- Hardness
Grain size tells you what colour a rock is.
Circle one: True False
Mia has a smooth white rock and a rough grey rock. Which sorting idea uses her surface observations?
- Sort by texture: smooth and rough
- Sort by weight: lighter and heavier
- Sort by size: smaller and larger
With adult help, you gently scratch a rock with your fingernail. A groove remains after loose powder is wiped away. What does this show?
- That part is harder than your fingernail
- That part is softer than your fingernail
- That part has larger grains than before
Two rocks can be the same colour but differ in resistance to scratching.
Circle one: True False
Sam sorts rocks by colour. Two rocks are grey, but one is rough and one smooth. Can they go in the same grey group?
- No, every group must match in all properties
- No, smooth rocks must go in a white group
- Yes, both match the chosen colour
Leo grouped rocks by colour. What should he do to compare their resistance to scratching?
- Try a gentle fingernail test with adult help
- Count how many samples are in each colour group
- Compare how large each sample looks beside a ruler

Answer key

For grown-ups. Fold this page away before handing over the rest.

Hardness · Hardness describes resistance to scratching. Crumbling is a different behaviour.
Texture · Texture is whether a rock feels rough or smooth when you touch it.
False · Grain size tells you how big or small the bits inside a rock are, not its colour.
Sort by texture: smooth and rough · Smooth and rough describe texture. Mia has not measured weight or compared size.
That part is softer than your fingernail · Your fingernail made a real scratch, so the scratched part is softer than the fingernail.
True · Colour and scratch resistance are different properties. Matching colour does not make every other property match.
Yes, both match the chosen colour · Both rocks fit the grey colour group. Their different textures do not break a rule based on colour.
Try a gentle fingernail test with adult help · A gentle scratch test compares resistance to scratching. Counting samples and comparing size test other things.