• 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 are stopped by plastic / They heat the equipment to 1000 °C / 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? (Background radiation comes from natural and man-made sources. / Beta particles are helium nuclei. / Alpha radiation is the most dangerous if the source is inside the body. / Gamma rays are part of the electromagnetic spectrum.) → Beta particles are helium nuclei.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: a uranium-235 nucleus splits after absorbing a neutron? (fission / fusion) → fissionPrompt: Fission splits; fusion joins.
2. In 2022 a US laser facility (the National Ignition Facility) reported a fusion milestone. What was it? (a fusion power station started supplying homes / fusion was achieved at room temperature / uranium was fused into gold / more fusion energy came out of the fuel than the laser energy delivered to it) → more fusion energy came out of the fuel than the laser energy delivered to itPrompt: It was a scientific gain, not yet electricity for the grid.

• 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. Fission and fusion: which statement is NOT true? (Both fission and fusion convert a small amount of mass into energy. / A nuclear power station can explode like a nuclear bomb. / Fusion releases energy in the Sun. / Fission products are usually radioactive.) → A nuclear power station can explode like a nuclear bomb.Prompt: Which process do working power stations use?
2. Fission or fusion: a uranium-235 nucleus splits after absorbing a neutron? (fission / fusion) → fissionPrompt: Fission splits; fusion joins.

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