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Logical Fallacies: Flaws in Reasoning

Students learn to spot logical fallacies — common errors in reasoning that make an argument sound convincing but fall apart under scrutiny — sharpening their ability to think critically and argue honestly.

Grade 9Argument50 minutes1 class periodReading WorkshopExplicit teaching4 StandardsCommon Core
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Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Define a logical fallacy.
  • ✓Identify common fallacies.
  • ✓Explain why each is flawed.
  • ✓Avoid fallacies in your own arguments.
Essential Question

An argument can sound totally convincing and still be completely broken. What are the sneaky reasoning tricks that fool us — and how do you catch them?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Fallacy Explorer · Interactive

The Fallacy Explorer

Project this and tap each fallacy. Have students learn how it works and find or write an example.

⚠️ Explore logical fallacies — tap eachTry it

The Lesson · Workshop (Mini-Lesson · Practice · Share)

50 minutes, five moves

Tap any phase to open the teacher moves and student actions.

1

Connect — Convincing but Wrong

5 min

How can an argument sound right and still be broken?

👩‍🏫 Teacher Moves

  • Present a fallacious argument.
  • Ask what’s wrong with it.
  • Set the goal: fallacies.

🎒 Student Actions

  • Hear the argument.
  • Sense the flaw.
  • Predict the idea.
2

Teach — Common Fallacies

12 min

Teacher models.

👩‍🏫 Teacher Moves

  • Define ad hominem, straw man.
  • Define bandwagon, false dilemma.
  • Define slippery slope.

🎒 Student Actions

  • Learn each fallacy.
  • Hear examples.
  • Spot the flaw.
3

Active Engagement — Explore Together

13 min

Class uses the Fallacy Explorer.

👩‍🏫 Teacher Moves

  • Tap each fallacy.
  • Identify fallacies in examples.
  • Explain the flaw.

🎒 Student Actions

  • Tap each one.
  • Identify fallacies.
  • Explain flaws.
4

Independent Practice — Independent Practice

15 min

Students spot fallacies.

👩‍🏫 Teacher Moves

  • Give arguments to analyze.
  • Name each fallacy.
  • Rewrite one without the flaw.

🎒 Student Actions

  • Name fallacies.
  • Explain them.
  • Fix one.
5

Share — Share

5 min

Students share a fallacy.

👩‍🏫 Teacher Moves

  • Invite a fallacy example.
  • Explain the flaw.
  • Hand out the exit ticket.

🎒 Student Actions

  • Share an example.
  • Explain the flaw.
  • Complete the exit ticket.
Standards Alignment

Built to the standards you report on

Aligned to the Common Core State Standards for English Language Arts (Grades 9–10).

CCSS
RI.9-10.8

Evaluate the argument in a text, identifying false statements and fallacious reasoning.

CCSS
RI.9-10.6

Determine an author’s point of view and analyze their rhetoric.

CCSS
W.9-10.1b

Develop claims and counterclaims fairly, supplying evidence.

CCSS
SL.9-10.3

Evaluate a speaker’s reasoning and use of evidence.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Fallacy cards with examples.
  • Sentence frame: “This is a ___ because ___.”
  • Match arguments to fallacies.

Support & Access

IEP / 504
  • Start with ad hominem and bandwagon.
  • Use clear examples.
  • Match example to fallacy.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Find fallacies in real ads or speeches.
  • Explain why fallacies persuade anyway.
  • Debate without fallacies.
Materials

What to gather

  • 📽️Projector / board
  • 📓Reading notebooks
  • 💻The Fallacy Explorer
  • 📰Ads & op-eds
  • ✏️Pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

logical fallacya flaw in reasoningad hominemattacking the person, not the argumentstraw mandistorting an argument to attack itbandwagon“everyone does it, so it’s right”false dilemmaoffering only two optionsslippery slopeclaiming disaster from one stepreasoningthe logic connecting ideasvalidlogically sound
Evaluate

Exit Ticket

Preview the three formative checks. Tap “Sample answer” to see what mastery looks like — hide them before you print for students.

QUESTION 1
What is a logical fallacy?
A flaw in reasoning that makes an argument sound convincing but weak or invalid.
QUESTION 2
“Don’t listen to her opinion on the budget — she’s a terrible singer.” What fallacy is this?
Ad hominem (attacking the person, not the argument).
QUESTION 3
Why is it important to recognize logical fallacies?
So you can think critically, avoid being fooled, and build stronger, honest arguments of your own.

Going deeper? Fallacy hunt.

Have students find logical fallacies in real advertisements, op-eds, or social media, and explain the flawed reasoning in each. A printable fallacy-hunt sheet is in the ELA library.

Study · Flashcards

Study the key terms

Tap a card to flip it, then rate whether you knew it. Built from this lesson’s vocabulary.

🃏 Logical FallaciesFlip
Card 1
Term
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Meaning
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Practice · Quiz

Check your understanding

A quick self-check with instant feedback, drawn from this lesson’s key terms.

📝 Logical FallaciesQuiz
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Question 1
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Practice · Worksheet

Printable worksheet

A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.

🖨️ Logical FallaciesPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: ad hominem, bandwagon, false dilemma, logical fallacy, reasoning, slippery slope, straw man, valid
  1. a flaw in reasoning
  2. the logic connecting ideas
  3. distorting an argument to attack it
  4. claiming disaster from one step
  5. “everyone does it, so it’s right”
  6. offering only two options
  7. attacking the person, not the argument
  8. logically sound

Part B · Show what you learned

  1. What is a logical fallacy?
  2. “Don’t listen to her opinion on the budget — she’s a terrible singer.” What fallacy is this?
  3. Why is it important to recognize logical fallacies?
Answer key — Part A: 1) logical fallacy · 2) reasoning · 3) straw man · 4) slippery slope · 5) bandwagon · 6) false dilemma · 7) ad hominem · 8) valid
Part B: 1) A flaw in reasoning that makes an argument sound convincing but weak or invalid. 2) Ad hominem (attacking the person, not the argument). 3) So you can think critically, avoid being fooled, and build stronger, honest arguments of your own.