• Quick retrieval from earlier learning (Identify gases with laboratory tests). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which gas gives this result: bubbled through limewater, it turns it milky? (hydrogen / oxygen / carbon dioxide / chlorine) → carbon dioxidePrompt: Each common gas has its own test.
2. Hydrogen peroxide decomposes with a catalyst and the gas relights a glowing splint. Which gas is it? (chlorine / carbon dioxide / oxygen / hydrogen) → oxygenPrompt: Hydrogen peroxide is H₂O₂.
3. Tests for gases: which statement is NOT true? (Oxygen relights a glowing splint. / Limewater is a solution of calcium hydroxide. / Chlorine turns limewater milky. / Hydrogen gives a squeaky pop with a lighted splint.) → Chlorine turns limewater milky.Prompt: Which gas pops and which relights a splint?

• Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
• Share the objective: Identify metal ions with flame tests and precipitates. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: A flame test gives a lilac flame. Which metal ion is present?
• Step 1: Potassium compounds give a lilac flame.
• Step 2: So the answer is: potassium, K⁺
• Answer: potassium, K⁺
• 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 flame test gives a green flame. Which metal ion is present? (potassium, K⁺ / copper, Cu²⁺ / lithium, Li⁺ / calcium, Ca²⁺) → copper, Cu²⁺Prompt: Fireworks use these colours.
2. Sodium hydroxide solution is added to a solution and a blue precipitate forms. Which metal ion is present? (copper(II), Cu²⁺ / iron(II), Fe²⁺ / iron(III), Fe³⁺ / calcium, magnesium or aluminium ions) → copper(II), Cu²⁺Prompt: Each transition metal ion gives its own coloured hydroxide.

• 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. Firework makers want a bright green colour. Which compounds should they add? (copper compounds / potassium compounds / lithium compounds / sodium compounds) → copper compoundsPrompt: Which metal ion gives a green flame?
2. A flame test gives a yellow flame. Which metal ion is present? (potassium, K⁺ / sodium, Na⁺ / copper, Cu²⁺ / calcium, Ca²⁺) → sodium, Na⁺Prompt: Fireworks use these colours.

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