• Quick retrieval from earlier learning (Reactants, products and word equations). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Complete the word equation: copper + oxygen → ___ (iron oxide / copper oxide / carbon dioxide / copper carbonate) → copper oxidePrompt: A metal reacting with oxygen makes a metal oxide.
2. In the reaction "iron + sulfur → iron sulfide", what are the reactants? (iron sulfide / sulfur and iron sulfide / iron and sulfur / iron only) → iron and sulfurPrompt: Reactants are on the left of the arrow.
3. Word equations: which statement is NOT true? (Products are the substances you start with. / Incomplete combustion can produce carbon monoxide, a poisonous gas. / Reactants are written on the left of the arrow. / Thermal decomposition breaks a substance down using heat.) → Products are the substances you start with.Prompt: Which side of the arrow is which?

• Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
• Share the objective: Balancing chemical equations. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Balance the equation. What number goes in the gap? __Al + 3Cl₂ → 2AlCl₃
• Step 1: 2Al + 3Cl₂ → 2AlCl₃
• Step 2: Al: 2 on the left, 2 on the right.
• Step 3: So the answer is: 2
• Answer: 2
• 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. Balance the equation. What number goes in the gap? Zn + __HCl → ZnCl₂ + H₂ → 2Prompt: Count the H atoms on each side.
2. 2Mg + O₂ → 2MgO How many Mg atoms are on the right side of this balanced equation? → 2Prompt: Multiply the big number in front by the small number after the symbol.

• 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. Balance the equation. What number goes in the gap? 2H₂O₂ → __H₂O + O₂ → 2Prompt: Count the H atoms on each side.
2. N₂ + 3H₂ → 2NH₃ How many H atoms are on the left side of this balanced equation? → 6Prompt: Multiply the big number in front by the small number after the symbol.

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