Rocks and Fossils: Tales from the Earth · Spring Term

Classifying Rocks

Students will observe and describe the physical characteristics of various rocks, such as their colour, texture, and whether they are hard or soft, and begin to classify them.

About This Topic

Fossils are the primary evidence we have for life on Earth millions of years ago. In Year 3, students learn the simple process of fossilisation: how an organism dies, is buried by sediment, and over a vast amount of time, its remains are replaced by minerals to become rock. This topic bridges the gap between biology and geology.

This unit aligns with the KS2 Science curriculum for Rocks and also touches on Evolution and Inheritance. Students learn why fossils are almost always found in sedimentary rock and what they can tell us about extinct species like dinosaurs or ammonites. This topic comes alive when students can physically model the patterns of fossilisation by creating their own 'fossil' casts and 'excavating' them.

Learning Objectives

• Classify rock samples into distinct groups based on observable properties like texture, hardness, and color.
• Compare and contrast the physical characteristics of at least three different types of rocks.
• Analyze how the properties of rocks influence their suitability for specific human uses, such as building or decoration.
• Predict which rock types would be most appropriate for constructing a stable wall, justifying the choice based on observed hardness and texture.

Before You Start

Properties of Materials

Why: Students need prior experience describing and comparing the physical properties of different materials, such as solids and liquids.

Introduction to Solids

Why: Understanding that rocks are solid objects with distinct physical attributes is foundational for classifying them.

Key Vocabulary

texture	The feel or appearance of a rock's surface, describing whether it is smooth, rough, grainy, or glassy.
hardness	A rock's resistance to being scratched or dented, indicating its durability and strength.
igneous rock	Rock formed from the cooling and solidification of molten rock (magma or lava), often appearing crystalline.
sedimentary rock	Rock formed from the accumulation and cementation of mineral or organic particles, often found in layers.
metamorphic rock	Rock that has been changed from its original form by heat, pressure, or chemical reactions, often showing banding or foliation.

Active Learning Ideas

Simulation Game: The Fossilisation Timeline

Students use layers of different coloured playdough to represent sediment burying a 'dinosaur' (a plastic toy). They 'squash' the layers and then carefully peel them back to see the impression left behind.

⏱ 30 min·Individual

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Gallery Walk: Mary Anning's Gallery

Display images of fossils found by Mary Anning on the Jurassic Coast. Students move around to identify what kind of creature each fossil might have been and what it tells us about the past.

⏱ 30 min·Pairs

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Think-Pair-Share: The Missing Pieces

Show a picture of a fossil skeleton. Students discuss in pairs why we usually only find bones and teeth as fossils, and what happened to the 'soft parts' like skin and muscles.

⏱ 15 min·Pairs

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Real-World Connections

Geologists examine rock samples from quarries to determine the best materials for building roads and foundations. For example, granite is often chosen for its hardness and durability in countertops and buildings.

Archaeologists study the types of rocks used in ancient structures, like the sandstone blocks of Petra or the limestone used in Egyptian pyramids, to understand construction techniques and trade routes of past civilizations.

Homeowners select specific types of rock, such as slate for roofing tiles or marble for fireplace surrounds, based on their aesthetic qualities and resistance to weathering.

Watch Out for These Misconceptions

Common Misconception

Fossils are actual bones that have just stayed there for a long time.

What to Teach Instead

Fossils are actually rock. The original bone has rotted away and been replaced by minerals. Using the term 'stone copy' helps students understand that the biological material is gone.

Common Misconception

You can find fossils in any kind of rock.

What to Teach Instead

Fossils are almost exclusively found in sedimentary rock. Igneous rock is too hot (it would melt the remains) and metamorphic rock usually squashes them beyond recognition. Sorting 'fossil-bearing' vs 'non-fossil' rocks helps clarify this.

Assessment Ideas

Exit Ticket

Provide students with three unlabeled rock samples. Ask them to write down one observable characteristic for each rock and then classify each rock as 'hard' or 'soft' based on their observations.

Discussion Prompt

Present students with images of different buildings or structures (e.g., a castle wall, a modern skyscraper, a garden path). Ask: 'Which types of rocks would be best for each of these structures and why? Consider their hardness and texture.'

Quick Check

Show students a collection of rock samples. Ask them to hold and feel each one, then sort them into two groups: 'smooth texture' and 'rough texture'. Circulate to check their sorting and ask why they placed each rock in its group.

Frequently Asked Questions

How long does it take for a fossil to form?

Fossilisation is a very slow process that usually takes millions of years. It requires very specific conditions, which is why most living things do not become fossils when they die.

Who was Mary Anning and why is she important?

Mary Anning was a pioneering British fossil hunter from Lyme Regis. She discovered the first ichthyosaur and plesiosaur skeletons. Her work was vital in helping scientists understand that animals could go extinct.

Why are fossils only found in sedimentary rocks?

Sedimentary rocks form at temperatures and pressures that are low enough to preserve the remains of living things. Igneous rocks are formed from molten lava, which would destroy any organic matter instantly.

How can active learning help students understand fossils?

Active learning, such as creating clay impressions or participating in a 'mock excavation', helps students visualise a process that takes millions of years. By physically layering 'sediment' or acting as 'palaeontologists', they engage with the sequence of events in fossilisation, making the concept of 'deep time' more accessible and less abstract.