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Science lesson plan · 8th grade (Year 9 in England) · 60 minutes

Exothermic and endothermic reactions

Chemical reactions, acids and bases

CCSS NGSS.MS-PS1-6CCSS NGSS.HS-PS1-4England: KS3 Chemistry: EnergeticsEngland: KS4 Combined Science: Energy changes in chemistry

Objective and success criteria

Students will: Exothermic and endothermic reactions.

  • 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: Rates of reaction; Reaction profiles: energy change and activation energy

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 · 6 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: copper + oxygen → ___ (carbon dioxide / copper chloride / copper oxide / iron oxide) → copper oxidePrompt: A metal reacting with oxygen makes a metal oxide.
  2. Methane burns completely in air: methane + oxygen → carbon dioxide + ___ (hydrogen / nitrogen / water / carbon monoxide) → 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. / Burning metal makes it lighter because mass is lost. / Reactants are written on the left of the arrow.) → Burning metal makes it lighter because mass is lost.Prompt: Which side of the arrow is which?

Hook · 6 min

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

I do: model it · 12 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Is this exothermic or endothermic: thermal decomposition of calcium carbonate?
  • Step 1: Endothermic reactions take in energy from the surroundings, so the temperature falls.
  • Step 2: So the answer is: endothermic
  • Answer: endothermic
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 12 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. Is this exothermic or endothermic: thermal decomposition of calcium carbonate? (exothermic / endothermic) → endothermicPrompt: Does it give out heat or take heat in?
  2. The temperature of a reaction mixture changes from 22 °C to 26 °C. What is the temperature change? (Use a minus sign for a fall.) → 4 °CPrompt: Change = final temperature − starting temperature.

You do: independent practice · 17 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 · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Is this exothermic or endothermic: photosynthesis? (exothermic / endothermic) → endothermicPrompt: Does it give out heat or take heat in?
  2. The temperature of a reaction mixture changes from 22 °C to 44 °C. What is the temperature change? (Use a minus sign for a fall.) → 22 °CPrompt: Change = final temperature − starting temperature.

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

  • Move on to: Rates of reaction; Reaction profiles: energy change and activation energy.
  • 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-8.

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

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Exothermic and endothermic reactions

Name

Date

Score/ 8

  1. Question 1

    The temperature of a reaction mixture changes from 19 °C to 4 °C. What is the temperature change? (Use a minus sign for a fall.)

    Answer°C

  2. Question 2

    Is this exothermic or endothermic: an instant cold pack?

    • A. exothermic
    • B. endothermic

  3. Question 3

    What is activation energy?

    • A. the minimum energy particles need to react when they collide
    • B. the energy in a battery
    • C. the energy given out by a reaction
    • D. the energy of light

  4. Question 4

    Is this exothermic or endothermic: burning methane?

    • A. exothermic
    • B. endothermic

  5. Question 5

    Breaking chemical bonds…

    • A. creates new atoms
    • B. takes in energy (endothermic)
    • C. has no energy change
    • D. gives out energy (exothermic)

  6. Question 6

    In an exothermic reaction, the energy of the products is…

    • A. lower than the energy of the reactants
    • B. exactly the same as the reactants
    • C. zero
    • D. higher than the energy of the reactants

  7. Question 7

    The temperature of a reaction mixture changes from 21 °C to 6 °C. What is the temperature change? (Use a minus sign for a fall.)

    Answer°C

  8. Question 8

    Is this exothermic or endothermic: thermal decomposition of calcium carbonate?

    • A. exothermic
    • B. endothermic

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Answer key: Exothermic and endothermic reactions

  1. 1. -15 °C

  2. 2. B. endothermic

  3. 3. A. the minimum energy particles need to react when they collide

  4. 4. A. exothermic

  5. 5. B. takes in energy (endothermic)

  6. 6. A. lower than the energy of the reactants

  7. 7. -15 °C

  8. 8. B. endothermic