Earth Materials Investigated

Overview

Students investigate how rocks are made of minerals and crystals, and how some contain fossils. They observe and test samples, classify earth materials, and connect their properties with human uses, including iron, aluminium, salts, mica, coal and petroleum.

Learning intentions

• WALT distinguish between minerals, rocks, crystals, fossils and earth deposits.
• WALT observe and test earth materials using evidence.
• WALT classify samples by their observable properties.
• WALT explain how properties influence the uses of earth materials.
• WALT describe Charles Cotton’s contribution to understanding New Zealand’s landforms.

Success criteria

• I can define and distinguish a mineral, rock, crystal, fossil and earth deposit.
• I can record careful observations and fair-test results using scientific vocabulary.
• I can classify a sample and justify my decision with evidence.
• I can link a material’s properties to a useful application.

Key vocabulary

Mineral, rock, crystal, fossil, earth deposit, natural material, property, colour, lustre, hardness, density, streak, texture, evidence, resource, geomorphology, landform.

Curriculum links

• Rocks are made of minerals and crystals and sometimes contain fossils.
• Earth deposits are natural materials with observable properties.
• Students recognise and describe the makeup of Earth materials to explain how minerals, crystals and fossils appear in rocks.
• Students evaluate observable properties to justify the selection and use of earth materials. This lesson also builds on earlier learning about Earth materials and landforms.

Lesson structure (60 minutes)

1. 0–5 min · Hook. Display a photograph of granite, a fossil-bearing limestone, aluminium foil and coal in the opening hook slide and ask, “Which of these is a rock, and which could be made from a rock?” Students make an individual prediction, then share one reason with a partner.

2. 5–15 min · Explicit teaching. Use the concepts and vocabulary slides to explain that a mineral is a naturally occurring substance with a particular composition; a rock is a naturally occurring solid made of one or more minerals; and a crystal is a solid whose particles form an ordered pattern, often visible as flat faces or repeated shapes. Explain that a fossil is preserved evidence of past life in rock, while an earth deposit is a naturally occurring concentration of a material such as minerals, coal or petroleum. Students complete a quick “rock, mineral, both or neither?” check with examples. Teacher note: clarify that a crystal is not automatically a rock, and that fossils are evidence of life rather than minerals.

3. 15–32 min · Hands-on investigation. Place students in five groups of five and provide labelled samples or photographs of granite, limestone, sandstone, quartz, mica, iron-bearing material, aluminium, coal and a fossil if available. Distribute the Earth materials investigation sheet. Students rotate roles—reader, equipment manager, observer, recorder and reporter—and record colour, lustre, texture, visible crystals or fossil evidence, and results from safe tests. Test hardness by scratching only with a teacher-approved object; test streak on an unglazed tile; estimate density by comparing similar-sized samples or using teacher-provided mass and volume data. Do not taste, sniff closely or break samples. Formative questions: “What is your evidence?” “Which observation is qualitative?” “How could we make this test fairer?” “Does colour alone identify a mineral?”

4. 32–42 min · Classification challenge. Students use their evidence to classify samples into groups such as likely mineral, rock made of several minerals, crystal-rich rock, fossil-bearing rock, or earth deposit. Groups must place each sample in one category and write a justification using “I classify this as… because…”. Invite two groups to defend different classifications and discuss why one property is rarely enough. Use the classification prompt slides to reveal suggested reasoning, not simply answers.

5. 42–52 min · Real-world applications. Present the comparison table in the materials and uses slides. Pairs decide which material is better for a lightweight structure: iron or aluminium. They compare strength, density, resistance to corrosion, cost and recyclability, then write a recommendation with evidence. Briefly connect salts to food and chemical processes, mica to electrical insulation and shiny products, coal to fuel, and petroleum to fuels and manufactured materials. Students identify one benefit and one environmental or sustainability consideration for one deposit.

6. 52–57 min · New Zealand connection. Introduce Charles Cotton as a New Zealand geographer and geomorphologist who studied how erosion, rivers, uplift and other processes shape landforms. Show a landform image in the Charles Cotton and Aotearoa slide. Students answer: “What evidence might a scientist collect to explain how this landform formed?” Emphasise that understanding Earth materials and processes helps people interpret landscapes and plan for hazards.

7. 57–60 min · Exit ticket. Students answer on the bottom of the investigation and exit-ticket sheet: “Explain the difference between a rock and a mineral”; “Give one observation that could help classify a sample”; and “Choose iron or aluminium for a bicycle frame and justify your choice.” Collect as students leave.

Resources

• the Earth materials investigation slide deck
• the Earth materials investigation sheet
• Rock, mineral, crystal, fossil and earth-deposit samples or clear photographs
• Hand lenses
• Unglazed tiles for streak testing
• Teacher-approved scratching tools
• Balance, measuring cylinders and water for teacher-supervised density data
• Rulers, pencils and group role cards
• Safety goggles, trays and paper towels

Assessment

• Listen for accurate use of mineral, rock, crystal, fossil and deposit during questioning and group explanations.
• Check investigation sheets for recorded observations, appropriate test results and evidence-based classification.
• Use the exit ticket to identify misconceptions and plan the next lesson.

Differentiation

• Provide a word bank, labelled sample photographs, sentence starters (“I observed…”, “This suggests…”) and partially completed comparison tables for students needing support or learning English.
• Allow students to record results through labelled drawings, oral explanation or scribed notes; use larger samples, hand lenses and a peer reading partner where needed.
• Extension: ask students to rank three properties by usefulness for identifying a sample and explain why; or investigate why density is more reliable than size when comparing materials.
• Pair students strategically and model one complete observation before group work. Do not require students with sensory or motor needs to handle samples; provide photographs and teacher-collected results.

Health and safety

• Wear goggles during testing; wash hands after handling samples.
• Do not taste, inhale, lick or rub materials near the face. Treat unknown samples as unsafe to handle directly.
• Use only teacher-approved tools, scratch away from people, and keep samples on trays.
• The teacher manages water, balances and any potentially dusty, sharp or heavy specimens. Avoid breaking rocks in class.