• Quick retrieval from earlier learning (How fossils form and what they reveal). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Why are fossils usually found in sedimentary rock, not igneous rock? (Igneous rock is too young / Animals never lived near volcanoes / Sedimentary rock is magnetic / Igneous rock forms from molten rock that would destroy remains) → Igneous rock forms from molten rock that would destroy remainsPrompt: Think about the temperature of magma.
2. Fossils: which statement is NOT true? (Fossils in deeper rock layers are usually older. / Fossils show that many species have become extinct. / Insects can be preserved in amber (fossilised tree resin). / Fossils are the actual bones, unchanged.) → Fossils are the actual bones, unchanged.Prompt: Did people ever meet a living T. rex?
3. Fossils of tropical ferns have been found in Antarctica. What is the best explanation? (The fossils were carried there by penguins / Ferns grow in ice today / Antarctica was once in a warmer location, before plate movement carried it south / Antarctica has always been tropical) → Antarctica was once in a warmer location, before plate movement carried it southPrompt: Continents move slowly over millions of years.

• Pass round different rocks and ask how each one might have formed.
• Share the objective: Use rock layers to put events in order. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Undisturbed rock layers, listed from the bottom up: D, C, E. Which layer is the youngest?
• Step 1: In undisturbed layers, the lowest is oldest and the highest is youngest.
• Step 2: So the answer is: E
• Answer: E
• 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. Undisturbed rock layers, listed from the bottom up: A, E, B, C. Which layer is the oldest? (A / C / B / E) → APrompt: Sediment settles on top of what is already there.
2. A crack filled with igneous rock (a dyke) cuts through layers A, B and C. What can you say about its age? (Its age cannot be compared / It is younger than all three layers / It is the same age as layer B / It is older than all three layers) → It is younger than all three layersPrompt: A layer must exist before something can cut through it.

• 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 8 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. Undisturbed rock layers, listed from the bottom up: E, A, D. Which layer is the oldest? (D / A / E) → EPrompt: Sediment settles on top of what is already there.
2. A crack filled with igneous rock (a dyke) cuts through layers A, B and C. What can you say about its age? (It is older than all three layers / It is younger than all three layers / Its age cannot be compared / It is the same age as layer B) → It is younger than all three layersPrompt: A layer must exist before something can cut through it.

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