Science // Earth's Systems

Properties of materials

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

Ages
7 to 8
Type
Concept
Builds on
1 topic
Leads to
7 topics
Standards
1 code

Quick check

Can the learner examine a collection of rocks and sort them by whether they're hard or crumbly, rough or smooth, and light or dark?

Ask this to see whether the topic is secure.

Topic // Mastery

What mastery looks like

What a learner can do once this topic is secure.
  • 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

Topic // Map

Where this fits

What to learn first and what this topic opens up, with the reason for each link. Required links come first.
  • RequiredMust come first
  • HelpfulHelps, but not essential

Before this

1 topic
  • Grouping MaterialsHelpful

    Matter & Materials // Ages 5 to 6

    Grouping materials by properties supports grouping rocks by properties

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Properties of materials

Ages 7 to 8 // Concept

Leads to

7 topics
  • How fossils formRequired

    Earth's Systems // Ages 7 to 8

    Must examine rocks before understanding how fossils form within rock

  • Rocks and soilRequired

    Earth's Systems // Ages 7 to 8

    Must know about rocks before learning that soil comes from broken-down rock

  • The Rock CycleRequired

    Matter & Materials // Ages 12 to 14

    The rock cycle requires prior knowledge of rock types (igneous, sedimentary, metamorphic) and their observable properties

  • Rapid earth changesHelpful

    Space Systems & Earth's History // Ages 7 to 8

    Rock knowledge supports understanding geological events

  • Types of RockHelpful

    Volcanoes & Earthquakes // Ages 7 to 9

    Volcanic rock types topic parallels curriculum rocks classification

  • Erosion and weatheringHelpful

    Earth's Systems // Ages 9 to 10

    Rock properties knowledge supports understanding how weathering breaks down different rocks

  • Rock Layers & Relative DatingHelpful

    Dinosaurs & Paleontology // Ages 9 to 11

    Understanding rock classification (sedimentary/igneous/metamorphic) helps understand strata and relative dating

Topic // Research-informed

Teaching notes

From the Marble Skill Taxonomy. These notes have not been validated in classrooms, so treat them as a starting point for your own judgement.

The approach

Children aged 7–8 learn to compare and group rocks by observable physical properties — hardness, texture (rough/smooth), colour, grain size, lustre (shiny/dull), and whether a rock crumbles. The central skill is choosing a property, sorting a collection by it, then RE-SORTING by a different property so learners discover that the same rocks group differently depending on the chosen criterion. Emphasis stays on evidence-based description ('this one is harder because it scratches that one') gathered with hands-on tests and hand lenses, and on observable properties rather than rock-type names (igneous/sedimentary come later): grouping precedes naming.

Common misconceptions

  • 'Rocks can only be sorted one right way' — not seeing that different properties give different valid groupings.
  • 'All grey rocks are the same rock' — grouping by colour alone and ignoring texture/hardness.
  • 'Bigger rocks are harder' — confusing size with hardness.
  • 'Shiny means precious/metal' — misreading lustre.
  • 'You can tell a rock's properties just by looking' — skipping the test (scratch/rub) that gives evidence.

Useful representations

  • A rock collection with hand lenses for direct observation.
  • A property sorting mat / Venn hoops (e.g. 'rough' vs 'smooth', 'hard' vs 'crumbly').
  • A comparison table: rock × property (hardness, colour, grain, texture).
  • A scratch-test / rub-test station for evidence gathering.

Teaching practices

  • Use real rock specimens and hand lenses — grouping rocks is a hands-on observation task, not a picture-only one.
  • Have children choose a property, sort, then RE-SORT by a different property so they see grouping depends on the chosen criterion.
  • Insist on evidence-based comparison (a scratch test for hardness, rubbing for texture) rather than guessing.
  • Build precise property vocabulary: hardness, texture, grain size, colour, lustre (shiny/dull), whether it crumbles.
  • Keep the focus on observable properties before rock-type names — classification by evidence comes before taxonomy.

Activities to try

  1. 1

    Test, describe and sort a rock collection

    Why it works: A grouping depends on the property you choose: the same collection of rocks can fall into different groups when you sort by a different observable property, though some rocks may stay together. Describing rocks by tested evidence is more reliable than guessing by looking.

    1. Examine a set of varied real rock specimens with a hand lens, looking closely at grain size and surface.
    2. For each rock, carry out simple evidence-gathering tests: a scratch test for hardness (which rock scratches which), a rub test for texture (rough or smooth), a tap or gentle press to see whether it crumbles or holds together, and note colour and lustre (shiny or dull).
    3. Record each rock's properties on a property card or a rock × property comparison table (hardness, colour, grain, texture).
    4. Choose one property and sort the whole collection into groups (e.g. rough vs smooth, or hard vs crumbly), using sorting hoops/Venn hoops or a sorting mat.
    5. Then re-sort the SAME rocks by a different property (e.g. switch from colour to hardness) and observe how the groups change.
  2. 2

    Compare two contrasting rocks

    Why it works: Rocks differ in several observable properties at once, so a single pair can be told apart and grouped in more than one way depending on which property you focus on.

    1. Take two clearly different rocks — for example one smooth, pale and crumbly, and one dark, heavy and very hard.
    2. Describe how each differs across several properties: hardness, texture, colour, grain size and weight.
    3. Decide and explain which group each rock would go into and why.
    4. Answer: are all rocks basically the same, or can they be sorted into groups? Give evidence.
  3. 3

    Is it really a rock?

    Why it works: Rocks are natural materials; bricks, concrete and manufactured glass (such as window or bottle glass) are made by people, often from rock materials, so they are not rocks even though they can be hard.

    1. Look at everyday manufactured items alongside rock specimens (e.g. a brick, concrete, glass).
    2. Decide whether each is a rock and give a reason.
    3. Discuss what makes something a natural rock versus a material made by people.

Topic // Standards

Curriculum standards

Codes for the curriculum statements this topic maps to. Each publisher owns its standard text.
The national curriculum in England: Key stages 1 and 2 framework document
Y3.Sci.R.1

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