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English lesson plan · 8th grade (Year 9 in England) · 45 minutes

Spotting faulty reasoning: bandwagon, slippery slope, ad hominem…

Reading Comprehension

CCSS RI.8.8CCSS RI.9-10.8England: KS3 Reading (evaluating arguments)England: GCSE English Language Paper 2England: AP Language

Objective and success criteria

Students will: Spotting faulty reasoning: bandwagon, slippery slope, ad hominem….

  • 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: Is the evidence relevant and sufficient?

Leads to: More faulty reasoning: straw man, circular reasoning, red herring…

Materials: A short text or extract (one copy each), Highlighters, Question cards, Mini whiteboards, A short model text on the board, Printed student sheet (below).

Warm-up · 5 min

  • Quick retrieval from earlier learning (Is the evidence relevant and sufficient?). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Judge the evidence for this claim. Claim: Cycling to school is safe in our town. Evidence: I cycled to school last Tuesday and nothing happened. (relevant and sufficient / relevant but not sufficient / not relevant) → relevant but not sufficientPrompt: Relevant: is the evidence actually about the claim?
  2. Which claim and evidence pair matches this judgement: relevant but not sufficient? (Claim: Cycling to school is safe in our town. Evidence: I cycled to school last Tuesday and nothing happened. / Claim: Cycling to school is safe in our town. Evidence: Police data shows no serious cycling accidents near local schools in five years, after new cycle lanes were built. / Claim: The new reading app improves reading scores. Evidence: The app has a colourful design that children like.) → Claim: Cycling to school is safe in our town. Evidence: I cycled to school last Tuesday and nothing happened.Prompt: Relevant: is the evidence actually about the claim?
  3. Judge the evidence for this claim. Claim: The beach needs more bins. Evidence: Seagulls are noisy birds. (relevant and sufficient / relevant but not sufficient / not relevant) → not relevantPrompt: Relevant: is the evidence actually about the claim?

Hook · 5 min

  • Read the first lines of a short text aloud and ask what students predict will happen and why.
  • Share the objective: Spotting faulty reasoning: bandwagon, slippery slope, ad hominem…. 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: Which fallacy matches this description? Presenting only two options when more exist.
  • Step 1: A fallacy is a flaw in reasoning that can make a weak argument sound convincing.
  • Step 2: false dilemma: Presenting only two options when more exist.
  • Step 3: So the answer is: false dilemma
  • Answer: false dilemma
  • 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. Which fallacy matches this description? Claiming something is right or good because lots of people do it or believe it. (hasty generalisation / bandwagon / slippery slope / ad hominem) → bandwagonPrompt: Think about what each kind of faulty argument does wrong.
  2. Which fallacy is used here? I met two rude tourists, so tourists are rude. (ad hominem / false dilemma / slippery slope / hasty generalisation) → hasty generalisationPrompt: Does it attack a person, follow the crowd, offer only two options, generalise from a few cases, or predict a chain of disasters?

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. Which fallacy is used here? My first two maths tests were hard, so all maths tests are impossible. (bandwagon / hasty generalisation / ad hominem / false dilemma) → hasty generalisationPrompt: Does it attack a person, follow the crowd, offer only two options, generalise from a few cases, or predict a chain of disasters?
  2. Type the fallacy (in English) that matches this description. Claiming something is right or good because lots of people do it or believe it. → bandwagonPrompt: Think about what each kind of faulty argument does wrong.

Watch out for

  • Answering from memory or opinion instead of evidence in the text.
  • Copying a long quote without explaining what it shows.

Support and stretch

Support

  • Review first: Is the evidence relevant and sufficient?.
  • Use concrete materials: a short text or extract (one copy each).
  • 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: More faulty reasoning: straw man, circular reasoning, red herring….
  • 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/english/grade-8.

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

eurekami

Spotting faulty reasoning: bandwagon, slippery slope, ad hominem…

Name

Date

Score/ 8

  1. Question 1

    Which fallacy matches this description? Drawing a big conclusion from too few examples.

    • A. hasty generalisation
    • B. false dilemma
    • C. ad hominem
    • D. slippery slope
  2. Question 2

    Which fallacy is used here? If we allow one food stall in the park, the whole park will become a car park.

    • A. ad hominem
    • B. slippery slope
    • C. false dilemma
    • D. hasty generalisation
  3. Question 3

    Type the fallacy (in English) that matches this description. Claiming something is right or good because lots of people do it or believe it.

    Answer

  4. Question 4

    Which fallacy is used here? Everyone in our year has this app, so it must be safe.

    • A. slippery slope
    • B. hasty generalisation
    • C. false dilemma
    • D. bandwagon
  5. Question 5

    Which fallacy matches this description? Presenting only two options when more exist.

    • A. hasty generalisation
    • B. slippery slope
    • C. false dilemma
    • D. ad hominem
  6. Question 6

    Which fallacy is used here? You're either with us or against us.

    • A. slippery slope
    • B. bandwagon
    • C. ad hominem
    • D. false dilemma
  7. Question 7

    Type the fallacy (in English) that matches this description. Drawing a big conclusion from too few examples.

    Answer

  8. Question 8

    Which fallacy matches this description? Claiming one small step will inevitably lead to a chain of extreme results.

    • A. ad hominem
    • B. hasty generalisation
    • C. slippery slope
    • D. false dilemma

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Answer key: Spotting faulty reasoning: bandwagon, slippery slope, ad hominem…

  1. 1. A. hasty generalisation

  2. 2. B. slippery slope

  3. 3. bandwagon

  4. 4. D. bandwagon

  5. 5. C. false dilemma

  6. 6. D. false dilemma

  7. 7. hasty generalisation

  8. 8. C. slippery slope