• Quick retrieval from earlier learning (Alpha, beta and gamma radiation). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which type of radiation: needs thick lead or concrete to reduce it? (alpha (α) / beta (β) / gamma (γ)) → gamma (γ)Prompt: The more ionising the radiation, the less penetrating it is.
2. Why are gamma rays used to sterilise medical equipment in sealed packs? (They pass through the packaging and kill microbes / They heat the equipment to 1000 °C / They are stopped by plastic / They make the equipment radioactive) → They pass through the packaging and kill microbesPrompt: Gamma is very penetrating.
3. Nuclear radiation: which statement is NOT true? (We can predict exactly when a particular nucleus will decay. / Gamma rays are part of the electromagnetic spectrum. / Background radiation comes from natural and man-made sources. / Radioactive decay is random.) → We can predict exactly when a particular nucleus will decay.Prompt: Which radiation needs lead to stop it?

• Show the periodic table and ask what patterns students can see before anything is explained.
• Share the objective: Nuclear fission and fusion. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Fission or fusion: used in today's nuclear power stations?
• Step 1: Fission splits a large nucleus into two smaller ones, releasing neutrons and energy.
• Step 2: So the answer is: fission
• Answer: fission
• 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. Fission or fusion: can cause a chain reaction? (fission / fusion) → fissionPrompt: Fission splits; fusion joins.
2. Why is fusion so hard to achieve on Earth? (Fusion only works with uranium / Nuclei repel each other, so extremely high temperatures and pressures are needed / There is no hydrogen on Earth / Fusion releases no energy) → Nuclei repel each other, so extremely high temperatures and pressures are neededPrompt: Both nuclei are positively charged.

• 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. How are control rods used in a fission reactor? (They cool the steam / They absorb neutrons to control the rate of the chain reaction / They produce electricity directly / They speed up all the neutrons) → They absorb neutrons to control the rate of the chain reactionPrompt: Fewer neutrons means fewer fissions.
2. Fission and fusion: which statement is NOT true? (Both fission and fusion convert a small amount of mass into energy. / Today's nuclear power stations use fusion. / A nuclear reactor uses a moderator to slow neutrons down. / Fusion releases energy in the Sun.) → Today's nuclear power stations use fusion.Prompt: Which process do working power stations use?

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