• Quick retrieval from earlier learning (Weathering and erosion). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which type of weathering is this: acid rain dissolving limestone? (physical weathering / chemical weathering / biological weathering) → chemical weatheringPrompt: Is it caused by temperature and ice, by a chemical reaction, or by living things?
2. What is the difference between weathering and erosion? (Weathering moves rocks to the sea / Weathering breaks rock down; erosion carries the pieces away / They are exactly the same / Erosion only happens in deserts) → Weathering breaks rock down; erosion carries the pieces awayPrompt: One breaks, the other moves.
3. Which happens quickly rather than over a long time? (a canyon forming / a mountain wearing down / a landslide / a river valley widening) → a landslidePrompt: Some changes to Earth take seconds; others take millions of years.

• Pass round different rocks and ask how each one might have formed.
• Share the objective: Physical, chemical and biological weathering. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Which type of weathering is this: water freezes in a crack, expands and splits the rock?
• Step 1: Physical weathering breaks rock into pieces without changing its chemicals.
• Step 2: So the answer is: physical (freeze–thaw, heating and cooling)
• Answer: physical (freeze–thaw, heating and cooling)
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. Which type of weathering is this: iron minerals in rock rust and crumble? (physical (freeze–thaw, heating and cooling) / chemical / biological) → chemicalPrompt: Is a living thing involved? Are new substances formed, or does the rock just break into pieces?
2. In which climate is freeze–thaw weathering most common? (where temperatures often go above and below 0 °C / in a tropical rainforest / in a hot desert that never freezes / under the sea) → where temperatures often go above and below 0 °CPrompt: Water must freeze and melt again and again.

• Students work on the student sheet. Circulate and check the first two answers of every student early.
• Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. Which type of weathering is this: rainwater, a weak acid, slowly dissolves limestone to form caves? (physical (freeze–thaw, heating and cooling) / chemical / biological) → chemicalPrompt: Is a living thing involved? Are new substances formed, or does the rock just break into pieces?
2. Weathering and erosion: which statement is NOT true? (Water shrinks when it freezes. / Rivers erode their banks and carry sediment. / Plant roots can split rocks. / Limestone caves form by chemical weathering.) → Water shrinks when it freezes.Prompt: What does water do when it freezes?

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-6.