• 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: ribosomes? (prokaryotic cells only / eukaryotic cells only / both types of cell) → both types of cellPrompt: “Pro-karyote” means “before nucleus”.
2. What shape is a DNA molecule? (a single straight line / a double helix / a ring of six atoms / a cube) → a double helixPrompt: It looks like a twisted ladder.
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? (120 times / 30 times / 300 times / 3 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 / read a person's thoughts / make copies of whole animals) → 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: “GM crops are unsafe to eat.” Which response is best supported by evidence? (All GM crops are identical, so one test proves everything. / Nobody has ever tested GM food. / Large reviews of studies have found approved GM foods as safe as conventional foods, but each new crop is tested separately. / A website says so, so it must be true.) → Large reviews of studies have found approved GM foods as safe as conventional foods, but each new crop is tested separately.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 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. Evaluate this claim: “Gene therapy can cure every inherited disease.” Which response is best supported by evidence? (It has never helped anyone. / Some gene therapies are approved for specific conditions, but many diseases are still being researched. / It only works on plants. / It changes the genes of every person on Earth.) → Some gene therapies are approved for specific conditions, but many diseases are still being researched.Prompt: Be wary of answers that use “never”, “every” or “always”.
2. A problem with selective breeding is… (inbreeding, which reduces variation and can increase inherited disorders / it creates new species every year / it is always too fast / it uses radioactive materials) → inbreeding, which reduces variation and can increase inherited disordersPrompt: Think about breeding closely related animals.

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