Rock Types Formation

Overview

In this lesson you will identify and classify igneous, sedimentary and metamorphic rocks, then connect each rock type to the processes and timescales that form them. This builds on earlier unit work by using observable properties to explain formation in the rock cycle.

Learning intentions

• Students will classify rocks as igneous, sedimentary or metamorphic using observable properties.
• Students will describe the key processes involved in the rock cycle that produce each rock type.
• Students will connect formation conditions (heat, pressure, time, and cooling) to rock properties and potential uses.
• Students will conduct a short, reproducible observation using a simple evidence table.

Success criteria

• I can sort rock samples or images into three rock types and explain my reasons.
• I can describe at least one process (e.g., weathering/erosion/deposition, melting/crystallisation, heat/pressure) linked to each rock type.
• I can use evidence from observable properties (texture, grain size, layering, fossils, foliation) to support my classification.

Curriculum links

• Science: Students describe key processes of the rock cycle, including timescales, and examine how rock properties reflect formation and influence use.
• Science (investigation and evidence): Students plan and conduct a small reproducible investigation using identified variables and safe, ethical handling of materials.
• Science (questioning): Students use investigable questions and predictions when sorting rocks using a key.
• Science (arguments with evidence): Students justify classifications using evidence and appropriate scientific reasoning.

Lesson structure (30 minutes)

1. 0–3 min · Hook (Think–Pair–Share). Teacher shows three labelled rock photos or samples (no names yet) and asks: “What clues can we see that might tell us how these rocks formed?” Students write one clue for each sample and share their best idea.

2. 3–10 min · Direct teach: observable properties. Teacher briefly models a “property-to-process” link using a simple board table:

• Igneous: visible crystals or glassy texture; often no layers; formed from melting and cooling.
• Sedimentary: layers/strata; may contain fossils or grains/pebbles cemented together; formed from weathering, erosion and deposition.
• Metamorphic: banding/foliation or changed texture; formed when rocks are heated and squeezed without melting completely. Students complete a guided notes sheet: for each rock type, they circle two properties they expect to see and one process that could create those properties.

3. 10–18 min · Rock key challenge (individual classification). Teacher provides a basic dichotomous key (paper or on the board) using only classroom-safe observations (e.g., layered? contains fossils? crystals visible? banded?). Students use the key to classify three provided rock samples (or images if samples are limited), recording: rock type chosen, key decision points, and one piece of supporting evidence.

4. 18–23 min · Mini investigation: evidence table (reproducible). Teacher prompts a quick, reproducible observation routine: “Same lighting, same magnifier, same steps, record same properties.” Students follow the routine and fill in a short evidence table (appearance, texture, any visible layering/fossils/banding) for one rock they feel least confident about, then decide again using the key.

5. 23–27 min · Explain using the rock cycle. Teacher asks: “How could this rock become another rock type?” Students choose one of their classified rocks and complete a short “rock cycle chain” with arrows: formation process → rock type, using at least one process term (weathering/erosion/deposition or melting/crystallisation or heat/pressure). Teacher circulates and checks for correct cause–effect.

6. 27–30 min · Exit ticket (Assessment). Students answer two questions:

• “State one observable property that helped you identify each rock type.”
• “Write one sentence describing how formation conditions affect a rock’s properties and usefulness.”

Resources

• Three rock samples and/or high-quality rock photos labelled A, B, C (ensure examples of each type)
• Simple dichotomous key printable or on-board version
• Student worksheet with property-to-process table and evidence table
• Hand lens or small magnifiers for close observation
• Safety glasses (if using physical samples) and paper towels/brushes for handling
• Coloured pencils or highlighters for circling properties
• Exit ticket slips or digital form (no hyperlinks)

Assessment

• Formative: teacher checks classifications during the rock key challenge and asks students to point to specific evidence for each decision point.
• Formative: review of evidence tables for correct use of observable properties and a clear justification.
• Summative (quick check): exit ticket responses assessing correct linking of rock properties to formation processes.

Differentiation

• Support: provide sentence starters for justifications (e.g., “I chose igneous because I can see… which suggests cooling after…”) and a simplified key with fewer branching options.
• Support: allow use of a word bank (weathering, erosion, deposition, melting, crystallisation, heat, pressure, layers, fossils, crystals, banding/foliation).
• Extension: ask an additional question for the most confident student: “Which rock type would you expect to find near a region with strong heat and pressure, and why?” (answer must cite evidence from properties).
• EAL/SEN considerations: use visuals and consistent model examples; accept responses in short phrases while maintaining correct scientific terminology.