• 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: a lighted splint gives a squeaky pop? (hydrogen / oxygen / carbon dioxide / chlorine) → hydrogenPrompt: Each common gas has its own test.
2. Why must the chlorine test be done in a fume cupboard? (Chlorine is invisible / Chlorine explodes / Chlorine is radioactive / Chlorine is toxic) → Chlorine is toxicPrompt: Think about safety.
3. Tests for gases: which statement is NOT true? (Hydrogen gives a squeaky pop with a lighted splint. / Limewater is a solution of calcium hydroxide. / Chlorine turns limewater milky. / Chlorine may turn damp blue litmus red before bleaching it.) → 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 crimson flame. Which metal ion is present? (sodium, Na⁺ / lithium, Li⁺ / calcium, Ca²⁺ / copper, Cu²⁺) → lithium, Li⁺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. Why should the wire loop be cleaned in acid before each flame test? (to remove traces of the last compound that could change the colour / to stop the wire melting / to make the flame hotter / to add sodium) → to remove traces of the last compound that could change the colourPrompt: Contamination gives false results.
2. A flame test gives a yellow flame. Which metal ion is present? (lithium, Li⁺ / 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.