• 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: a single loop of DNA not in a nucleus? (prokaryotic cells only / eukaryotic cells only / both types of cell) → prokaryotic cells onlyPrompt: “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? (3 times / 120 times / 300 times / 30 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. A problem with selective breeding is… (it uses radioactive materials / it creates new species every year / inbreeding, which reduces variation and can increase inherited disorders / it is always too fast) → inbreeding, which reduces variation and can increase inherited disordersPrompt: Think about breeding closely related animals.
2. Evaluate this claim: “GM crops are unsafe to eat.” Which response is best supported by evidence? (Nobody has ever tested GM food. / All GM crops are identical, so one test proves everything. / 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 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. Farmers breed only the cows that give the most milk, generation after generation. What is this called? (cloning / genetic engineering / selective breeding (artificial selection) / natural selection) → selective breeding (artificial selection)Prompt: Humans choose which animals reproduce.
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. / 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. / 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.Prompt: Be wary of answers that use “never”, “every” or “always”.

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