Moles and Reacting Masses — Interactive Lesson (Ages 14–16)

How do chemists know exactly how much to use? They count atoms by weighing them. This 21-slide interactive lesson on reacting masses takes pupils from first ideas to exam-style explanations, with 13 self-marking activities and nothing to prepare beforehand.

Teaching Moles and Reacting Masses in GCSE Chemistry

Pupils calculate relative formula mass from relative atomic masses, meet the mole and the Avogadro constant, and use moles = mass ÷ Mr to convert between mass and moles. Step-by-step worked examples, including the thermal decomposition of limestone in cement works, show how to use balanced equations to calculate reacting masses, before pupils identify limiting reactants and apply conservation of mass.

What Pupils Will Learn

• Calculate relative formula mass (Mr) from relative atomic masses.
• Describe the mole and the Avogadro constant.
• Use moles = mass ÷ Mr to convert between mass and moles.
• Use balanced equations to calculate reacting masses.
• Explain the idea of a limiting reactant.

What’s Included

• 21-slide interactive lesson
• 13 self-marking activities: multiple-choice questions, true-or-false checks, sorting tasks and fill-in-the-gap questions
• Step-by-step teaching cards that reveal one point at a time
• A written explanation task with a model answer for self-assessment

Why Teachers Love It

• No prep — open it on an interactive whiteboard, laptop or tablet
• Instant feedback explains every answer, right or wrong
• Everyday examples make chemistry feel real
• Works for whole-class teaching, independent study or revision

Curriculum Alignment

Supports UK GCSE Chemistry and Combined Science (AQA, Edexcel and OCR) and the Nigerian Senior Secondary Chemistry curriculum (SS1–SS2), including WAEC and NECO exam preparation.

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FAQ

What year groups is this for? Years 10–11 (ages 14–16), and SS1–SS2 in Nigeria.

Is it self-marking? Yes — all 13 activities give instant feedback.

Do pupils need to log in? No. The lesson runs in any modern web browser.

Can I use it for revision? Yes. Pupils can replay it as often as they like, and the results screen shows which questions to review before a test.