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Science lesson plan · 7th grade (Year 8 in England) · 45 minutes

Combustion, oxidation and the fire triangle

Chemical reactions, acids and bases

CCSS NGSS.MS-PS1-2England: KS3 Chemistry: Chemical reactions

Objective and success criteria

Students will: Combustion, oxidation and the fire triangle.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Reactants, products and word equations

Leads to: the next skill in this area.

Materials: Teacher demo or video, Indicator color chart, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 5 min

  • 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: magnesium + oxygen → ___ (carbon dioxide / magnesium chloride / magnesium oxide / magnesium carbonate) → magnesium oxidePrompt: A metal reacting with oxygen makes a metal oxide.
  2. Methane burns completely in air: methane + oxygen → carbon dioxide + ___ (carbon monoxide / water / nitrogen / hydrogen) → waterPrompt: Methane contains carbon and hydrogen. What does hydrogen become when it burns?
  3. Word equations: which statement is NOT true? (Combustion is a reaction with oxygen. / Incomplete combustion can produce carbon monoxide, a poisonous gas. / Products are the substances you start with. / Thermal decomposition breaks a substance down using heat.) → Products are the substances you start with.Prompt: Which side of the arrow is which?

Hook · 5 min

  • Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
  • Share the objective: Combustion, oxidation and the fire triangle. Read the success criteria together.

I do: model it · 10 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Complete the word equation: calcium + oxygen → ?
  • Step 1: metal + oxygen → metal oxide
  • Step 2: So the answer is: calcium oxide
  • Answer: calcium oxide
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 10 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. Complete the word equation: aluminium + oxygen → ? → aluminium oxidePrompt: When a metal reacts with oxygen it forms an oxide.
  2. Why is a gas boiler with a poor air supply dangerous? (It produces too much oxygen / It stops producing heat completely / Incomplete combustion produces toxic carbon monoxide / It makes the water too pure) → Incomplete combustion produces toxic carbon monoxidePrompt: What forms when there is not enough oxygen?

You do: independent practice · 10 min

  • 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.

Exit ticket · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Complete the word equation: sodium + oxygen → ? → sodium oxidePrompt: When a metal reacts with oxygen it forms an oxide.
  2. Combustion: which statement is NOT true? (Combustion is a reaction with oxygen that releases energy. / Rusting is a slow oxidation reaction. / A fire can burn without oxygen. / Burning fossil fuels releases carbon dioxide.) → A fire can burn without oxygen.Prompt: Is energy taken in or given out when something burns?

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Reactants, products and word equations.
  • Use concrete materials: teacher demo or video.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-7.

Free lesson plan from eurekami.com/lesson-plan-builder

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Combustion, oxidation and the fire triangle

Name

Date

Score/ 8

  1. Question 1

    Combustion: which statement is NOT true?

    • A. Rusting is a slow oxidation reaction.
    • B. Combustion is a reaction with oxygen that releases energy.
    • C. Hydrogen burns to make only water.
    • D. A fire can burn without oxygen.

  2. Question 2

    Complete the word equation: magnesium + oxygen → ?

    Answer

  3. Question 3

    A fire blanket is thrown over a burning pan. Which side of the fire triangle does it remove?

    • A. oxygen
    • B. none
    • C. fuel
    • D. heat

  4. Question 4

    Complete the word equation: sodium + oxygen → ?

    Answer

  5. Question 5

    Firefighters cut a firebreak (a strip with no trees) in front of a wildfire. Which side of the fire triangle does this remove?

    • A. oxygen
    • B. water
    • C. heat
    • D. fuel

  6. Question 6

    Complete the word equation: zinc + oxygen → ?

    Answer

  7. Question 7

    Why is a gas boiler with a poor air supply dangerous?

    • A. It stops producing heat completely
    • B. It produces too much oxygen
    • C. It makes the water too pure
    • D. Incomplete combustion produces toxic carbon monoxide

  8. Question 8

    Complete the word equation: aluminium + oxygen → ?

    Answer

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Answer key: Combustion, oxidation and the fire triangle

  1. 1. D. A fire can burn without oxygen.

  2. 2. magnesium oxide

  3. 3. A. oxygen

  4. 4. sodium oxide

  5. 5. D. fuel

  6. 6. zinc oxide

  7. 7. D. Incomplete combustion produces toxic carbon monoxide

  8. 8. aluminium oxide