---
title: "Properties of rocks"
description: "Compare and group different kinds of rocks based on their appearance and simple physical properties such as hardness, texture, and colour"
canonical: https://lightmysky.com/learn/science/properties-of-rocks-mt_R6YoRXkRxS
source: https://lightmysky.com/learn/science/properties-of-rocks-mt_R6YoRXkRxS.md
retrieved: 2026-11-12
---

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# Properties of rocks

Compare and group different kinds of rocks based on their appearance and simple physical properties such as hardness, texture, and colour

Subject: Science · Area: Earth's Systems · Ages 7 to 8
Page: https://lightmysky.com/learn/science/properties-of-rocks-mt_R6YoRXkRxS

## Ready when they can

- 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

## Lesson: Sorting rocks by their properties

Rock samples have properties you can compare. Grains are pieces or crystals that make up a rock. Grain size describes how large or small they are, not their colour. Some grains are too small to see without help.

Texture describes how a surface feels, such as rough or smooth. Colour describes what you see, such as grey or red. Hardness describes resistance to scratching. Breaking or crumbling is a different behaviour. Different grains in one rock can have different hardness.

*(drawing: Keep a property name with its observation. These words do not measure hardness.)*

Ask an adult to choose safe samples for a gentle fingernail test. A real scratch is a groove that remains after loose powder is wiped away. A scratched part is softer than your fingernail. If no groove forms, it resisted this test. Do not hit or taste rocks, or breathe rock dust. Wash your hands afterwards.

To sort rocks, choose one property and check every sample. For texture, use rough and smooth groups. For colour, use groups such as grey and red. Two grey rocks belong together in a grey group even if their textures differ.

*(drawing: Use the same chosen property for every sample.)*

**Example.** Two white rock samples can react differently to a scratch test. One may show a groove while the other resists scratching. Their colour matches, but their scratch resistance differs. Those observations alone do not tell you what kinds of rocks they are.

**Recap.** Check hardness, texture, colour, and grain size, then sort your rocks into groups.

*This lesson, its questions, and its flashcards were written for this dataset.*

## Practice

8 questions on this page, each with its working shown.

## Optional connections

- [Grouping Materials](https://lightmysky.com/learn/science/grouping-materials-mt_SwaNNdm_Ks)

## Opens up

- [How fossils form](https://lightmysky.com/learn/science/how-fossils-form-mt_mwirOvigWD)
- [The Rock Cycle](https://lightmysky.com/learn/science/the-rock-cycle-mt_NckKLZ3uCE)
- [Types of Rock](https://lightmysky.com/learn/science/types-of-rock-mt_NYA50DFcOO)
- [Erosion and weathering](https://lightmysky.com/learn/science/erosion-and-weathering-mt_vAP_A986IQ)
- [Rocks and soil](https://lightmysky.com/learn/science/rocks-and-soil-mt_yhhprm7dZK)
- [Fast and slow Earth changes](https://lightmysky.com/learn/science/fast-and-slow-earth-changes-mt_ZJu8s-Q1xa)