• Quick retrieval from earlier learning (Prokaryotic and eukaryotic cells; DNA, genes and chromosomes). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Where is this found: cytoplasm? (prokaryotic cells only / eukaryotic cells only / both types of cell) → both types of cellPrompt: “Pro-karyote” means “before nucleus”.
2. Where is DNA found in an animal cell? (in the cell wall / outside the cell / in the chloroplasts / mainly in the nucleus) → mainly in the nucleusPrompt: It is the control centre of the cell.
3. A bacterial cell is about 2 µm long and a cheek cell is about 60 µm. How many times longer is the cheek cell? (300 times / 3 times / 30 times / 120 times) → 30 timesPrompt: Divide the larger size by the smaller one.

• Show a microscope image of cells and ask what students think they are looking at.
• Share the objective: Selective breeding, genetic engineering and gene editing. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: What does CRISPR-Cas9 allow scientists to do?
• Step 1: CRISPR uses guide RNA to direct Cas9 to a target sequence, where the DNA is cut and edited.
• Step 2: So the answer is: cut DNA at a chosen place to edit a gene precisely
• Answer: cut DNA at a chosen place to edit a gene precisely
• 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. What does CRISPR-Cas9 allow scientists to do? (cut DNA at a chosen place to edit a gene precisely / remove all mutations from a population / make copies of whole animals / read a person's thoughts) → cut DNA at a chosen place to edit a gene preciselyPrompt: Cas9 is an enzyme guided by a short piece of RNA.
2. Evaluate this claim: “Insect-resistant GM crops mean farmers never need to manage pests again.” Which response is best supported by evidence? (They can reduce insecticide spraying, but insects can evolve resistance, so careful management is still needed. / Pests disappear forever after one season. / The crops kill every animal that touches them. / Insects cannot evolve.) → They can reduce insecticide spraying, but insects can evolve resistance, so careful management is still needed.Prompt: Be wary of answers that use “never”, “every” or “always”.

• 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 7 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. Evaluate this claim: “Selective breeding is new and unnatural.” Which response is best supported by evidence? (It uses CRISPR to cut DNA. / It was invented in the last ten years. / Humans have selectively bred crops and animals for thousands of years; for example, maize was bred from a wild grass called teosinte. / It only works on bacteria.) → Humans have selectively bred crops and animals for thousands of years; for example, maize was bred from a wild grass called teosinte.Prompt: Be wary of answers that use “never”, “every” or “always”.
2. What does CRISPR-Cas9 allow scientists to do? (make copies of whole animals / read a person's thoughts / cut DNA at a chosen place to edit a gene precisely / remove all mutations from a population) → cut DNA at a chosen place to edit a gene preciselyPrompt: Cas9 is an enzyme guided by a short piece of RNA.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-11.