• Quick retrieval from earlier learning (Match cell parts to the jobs they do). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which part of a cell matches this description: jelly-like liquid where most chemical reactions take place? (cytoplasm / mitochondria / permanent vacuole / cell wall) → cytoplasmPrompt: Think about which part controls, which part makes energy available and which part lets things in and out.
2. What does the nucleus do? (a rigid layer of cellulose that strengthens the cell / where proteins are made / jelly-like liquid where most chemical reactions take place / controls what the cell does) → controls what the cell doesPrompt: Match the name to its job, not to where it is.
3. A plant that is not watered wilts (droops). Which part of its cells has lost water? (the permanent vacuole / the ribosomes / the nucleus / the chloroplasts) → the permanent vacuolePrompt: Which part is full of cell sap?

• Show a microscope image of cells and ask what students think they are looking at.
• Share the objective: Prokaryotic and eukaryotic cells. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Where is this found: a single loop of DNA not in a nucleus?
• Step 1: Prokaryotes (bacteria) have no nucleus: their DNA is a single loop, often with extra rings called plasmids.
• Step 2: So the answer is: prokaryotic cells only
• Answer: prokaryotic cells only
• 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. Where is this found: cell membrane? (prokaryotic cells only / eukaryotic cells only / both types of cell) → both types of cellPrompt: “Pro-karyote” means “before nucleus”.
2. Why can antibiotics kill bacteria without harming human cells? (Bacteria have a nucleus that absorbs the drug / They target structures or processes that only bacterial cells have / Human cells have no ribosomes / Antibiotics only work outside the body) → They target structures or processes that only bacterial cells havePrompt: Bacterial cell walls and ribosomes differ from ours.

• 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. A bacterial cell is about 2 µm long and a cheek cell is about 60 µm. How many times longer is the cheek cell? (30 times / 300 times / 120 times / 3 times) → 30 timesPrompt: Divide the larger size by the smaller one.
2. Prokaryotes and eukaryotes: which statement is NOT true? (Both prokaryotic and eukaryotic cells have ribosomes. / Bacterial cells are much smaller than most animal and plant cells. / Some bacteria have a flagellum to move. / Plasmids are found in human cells.) → Plasmids are found in human cells.Prompt: Do bacteria have mitochondria?

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.