Lesson: Fossils

Year: 6 | Subject: Science | Time Allocation: 100%

Class/Set: ____________ Date/Term: ____________

LO (WALT): To describe how fossils are formed when organisms that have lived are trapped within sedimentary rock.

Success Criteria (WILF):

1. I can sequence the four main stages of the fossilisation process.
2. I can explain the role of sedimentary rock and mineralisation in preserving remains.
3. I can identify why only a small fraction of living things become fossils.

1. Starter (15%)

• Activity: 'Fact or Fiction' Retrieval.
• Action: Display five statements on the board regarding fossils (e.g., "Fossils are made of bone," "All animals become fossils when they die"). Students use mini-whiteboards to write 'Fact' or 'Fiction'.
• Discuss: Briefly address the misconception that fossils are bone; clarify that they are rock 'models' of original remains.

2. Main Activity (70%)

Teacher Input:

• Explain: Use a visual diagram to show an ammonite dying and sinking to the sea floor. Emphasise the need for rapid burial to prevent scavenging.
• Model: Describe the process of 'Permineralisation'. Explain how layers of sediment build up over millions of years, and how water carrying minerals seeps into the hard remains (bones/shells), replacing the organic matter with rock.
• Demonstrate: Show a WAGOLL (What A Good One Looks Like) of a sequenced flow map. Point out technical Tier 3 vocabulary: sediment, mineralisation, erosion, and sedimentary rock.
• Check: Ask students to explain to a partner why we rarely find fossils of soft-bodied creatures like jellyfish.

Student Task:

• Task A (Sequencing): Create a four-stage annotated diagram of the fossilisation process.
• Sequence: 1. Death and Burial; 2. Sedimentation; 3. Mineralisation; 4. Erosion and Discovery.
• Task B (Analysis): Complete the 'Conditions for Success' table. Students must identify why specific environments (e.g., riverbeds vs. mountain tops) are better for fossilisation.
• Challenge (Greater Depth): Write a short paragraph explaining how fossils provide evidence for the theory of evolution, using the term 'chronological sequence'.

Environment	Fossil Potential	Reason
Sea Floor	High	Rapid burial by silt.
Rainforest	Low	High decay/acidity.
Mountain	Low	High erosion/no burial.

3. Plenary (15%)

• Check: 'The 100-Million-Year Question'. Ask: "If we find a fossil on top of a mountain, what does that tell us about the Earth's crust?"
• Reflect: Students self-assess against the WILF criteria using a 'Traffic Light' system in their exercise books.

4. Resources

• Visual slides showing the fossilisation process.
• Selection of real fossils (if available) or high-quality images of ammonites and trilobites.
• Science exercise books and HB pencils.
• Mini-whiteboards and pens.

---

⚠ TEACHER’S GUIDANCE

💡 Pedagogical Insights

• Misconception Alert: Students often believe fossils are the actual bones of the animal. Explicitly teach that the organic material is replaced by minerals over millions of years—the fossil is a rock replica.
• Delivery Note: For Year 6, ensure you link this to their 'Evolution and Inheritance' unit. Fossils are the primary evidence used to observe how species have changed over time.
• Safety & Nuance Check: If handling real fossils, ensure students are supervised as some specimens can be heavy or have sharp edges. Always wash hands after handling geological samples.

✅ Answer Key & Solutions

• Starter (Fact or Fiction):
  1. "Fossils are made of bone" - Fiction (They are mineralised rock).
  2. "Sedimentary rock is where fossils are found" - Fact.
• Task A (Sequencing Logic):
  1. Death: Organism dies and sinks.
  2. Burial: Layers of sediment (mud/sand) cover the body.
  3. Mineralisation: Soft parts rot; minerals replace hard parts.
  4. Discovery: Earth moves and erosion reveals the fossil.
• Task B (Conditions Table):
  • Sea Floor Answer: High potential due to constant deposition of sediment.
  • Rainforest Answer: Low potential because the warm, wet environment causes rapid decay before burial can occur.
• Challenge Answer: Fossils show a 'chronological sequence' because older fossils are found in deeper rock layers (stratigraphy), allowing scientists to see how body structures have adapted over millions of years.