Year 3 Science: Different kinds of rock
Part of the Year 3 Science rocks, fossils and soils chapter. Chapter overview · whole chapter on one page
Different kinds of rock
A rock is a hard, natural material that is found in the ground. Rocks come in many different kinds. Scientists compare rocks by how they look:
- colour: the colour of the rock;
- texture: how the rock looks and feels, for example smooth, rough, crumbly or gritty;
- layers: flat bands, one on top of another;
- sparkly crystals and holes.
Two rocks can be the same colour and still be very different. Look at the six samples in the picture.
Key ideas
- A rock is a hard, natural material found in the ground.
- Rocks can be compared and grouped by their colour, texture, layers, sparkly crystals and holes.
- Texture means how a rock looks and feels: smooth, rough, crumbly or gritty.
- Two rocks can look alike in one way, and be different in another way.
Method. Find the samples that have layers, then find the dark grey one.
- Find the layers. Samples A and D have flat layers.A, D
- Find the colour. Sample A is dark grey. Sample D is light brown.A is dark grey
- Choose the one that matches both. Sample A has layers and is dark grey.A
- Write the answer. A
Check. Sample D has layers, but it is light brown, not dark grey. ✓
Watch out. Use both clues. Colour alone is not enough.
Method. Look for the small white sparkles in the samples.
- Look at each sample. Sample C has small white sparkles and black dots.sparkles on C
- Check the others. None of the other samples has sparkles.only C
- Write the answer. So the sample with sparkly crystals is C.C
- Write the answer. C
Check. Sample E has holes, not sparkles. ✓
Method. Find the samples whose texture is smooth.
- Read the textures. Samples A and F are smooth. The others are rough, gritty or crumbly.A and F
- Write the answer. So the two smooth samples are A and F.A, F
- Write the answer. A, F
Check. Sample F is smooth and shiny, with thin lines. ✓
Watch out. Smooth is about the texture. Layers and colour are different clues.
Watch out
Watch out: grey does not mean the same kind of rock. Look at the texture, the layers and the holes too, as well as the colour.
Try it at home or school (with a grown-up). Look at stones you already have at home, or in a garden you are allowed to use. Do not collect stones from walls, cliffs or protected places. Sort them into two groups: stones with stripes or layers, and stones without. Wash your hands afterwards.
Exam tip
Grown-up tip. Ask: “How does this stone feel? Is it smooth, rough or gritty? Does it have stripes?” Let your child use the words texture and layers.
Exercise 7A Different kinds of rock
Method. Find the white samples, then the crumbly one.
- Find the white samples. Samples B and F are white.B and F
- Choose the crumbly one. Sample B is crumbly. Sample F is smooth and shiny.B
- Write the answer. B
Check. Sample F is smooth, not crumbly. ✓
Method. Look for dark spots inside the samples.
- Look at each sample. Sample E has small holes in its surface.holes on E
- Write the answer. E
Check. No other sample has holes. ✓
Method. Look for small white sparkles.
- Look at each sample. Sample C has small white sparkles.sparkles on C
- Write the answer. C
Check. Sample C is grey, with black and white dots. ✓
Method. Look for flat bands in each sample.
- Look at each sample. Samples A and D have flat bands, one on top of another.A, D
- Write the answer. A, D
Check. The other four samples have no layers. ✓
Method. Find the light brown sample, then check its grains.
- Find the light brown one. Sample D is light brown.D
- Check the grains. Sample D is gritty, with tiny grains.tiny grains
- Write the answer. D
Check. Sample A is dark grey, so it is not light brown. ✓
Method. Look at the texture of each sample.
- Read the textures. Samples A and F are smooth.A, F
- Write the answer. A, F
Check. The others are rough, gritty or crumbly. ✓
Method. Find the red-brown sample.
- Read the picture. Sample E is red-brown and has holes.E
- Write the answer. E
Check. Sample E is the only red-brown sample. ✓
Method. Find the smooth, shiny sample.
- Read the picture. Sample F is smooth and shiny, with thin lines.F
- Write the answer. F
Check. Sample F is white. ✓
Method. Think about what else can be different about two rocks.
- Think about colour. Two rocks can both be grey and still look different.both grey
- Decide. Texture, layers and holes can be different too, so Kofi is not right.no
- Write the answer. no
Check. Colour is only one of the ways to compare rocks. ✓
Method. Think about the ways to compare rocks in this section.
- Read the list. Texture, layers, sparkly crystals and holes can all be checked by looking or feeling.texture or layers
- Write the answer. Accept any one of: texture, layers, sparkly crystals, holes, how hard it is.
Check. Compare the rocks in the same way, so the test is fair. ✓
Method. Find the samples with flat bands.
- Read the picture. Samples A and D have layers.A, D
- Write the answer. A, D
Check. Samples A and D have flat bands. ✓
Method. Find the samples without flat bands.
- Read the picture. Samples B, C, E and F have no layers.B, C, E, F
- Write the answer. B, C, E, F
Check. Four samples have no layers, and two have layers. ✓
Method. Think about the holes and how hard the rock is.
- Think about sample E. Sample E has small holes in it.holes
- Give the reason. Sample E is hard, so holes do not make a rock soft.hard
- Write the answer. No. Accept any reason that says sample E has holes but is hard, so holes do not make a rock soft.
Check. Hardness and holes are two different properties. ✓