Faulty Logic: Overgeneralization

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SWBAT write examples of opinions with errors in reasoning about a given topic.

Big Idea

Students use critical thinking skills to detect faulty logic in arguments. Non-examples help students learn, too!

Motivational Hook

20 minutes

In order to teach the Common Core writing standards of using reasoning to support opinions, I guide students to explore faulty logic examples in this unit.  Faulty logic is an argument that lacks validity. It is sometimes referred to as paradoxical reasoning because it is illogical, absurd, or contradictory.  Not only will they need to recognize faulty logic so as to avoid using it in their own opinion writing, later they will also be expected to assess reasoning provided by the author and determine if the evidence is based on fallacious reasoning as they enter middle school and high school in preparation for research in their careers or college. Students need to build on prior knowledge to get to that point.  Starting to introduce errors in logic in the primary grades gives students the foundational knowledge needed for this critical reasoning later on.

Although the concept of faulty logic and errors in reasoning is not often taught until later grades, I decided to present my gifted, high achieving class with this challenge.  It is an experiment of sorts for my class consisting of students who are out-of-the-box thinkers. The tricky part is teaching students through non-examples. This non-traditional route of teaching shows students what not to do instead of what to do.  Students use critical thinking skills as they analyze the irrationality of their writing. This activity is a demonstration of the old adage "Learn from your mistakes." Indeed, mistakes provide opportunities for learning.

I begin my introduction of overgeneralization with a video to hook students into the lesson.  Videos are such powerful media to entice students into lessons that I use them frequently and successfully.  I show an Overgeneralization commercial that I downloaded prior to this lesson so students can analyze an example.  The commercial is for a cookie dough, advertising that you will ALWAYS want this specific brand of cookie dough.  I ask students for their opinions supported by scenes from the video commercial.  Common Core encourages students to notice and critique when texts make claims supported by written or digital evidence.  After our discussion, I asked students to consider how strong/valid the evidence or supports are for the argument in the video.

2nd grade students are not used to questioning the effectiveness of reasoning and supports.  They often take information in at face value.  Students learn to be critical thinkers through practice.  Critical analysis of a source is a great way to start.

Introduction to Overgeneralzation

20 minutes

This lesson focuses on the writing standard of writing opinion pieces supplying reasons that support the opinion.  Only in this case, the supports are non-examples because they are faulty logic or illogical.

Students need background information.  I need to know how much background information to give them.  What better way to find out than to assess their prior knowledge.  I use an Overgeneralization Flipchart to guide my lesson sequentially.  The first part of my lesson involves finding out what students already know and want to know about overgeneralization. Integrating technology, I ask students to text me these two sections using student assigned transponders.  I number my transponders and know which students have the corresponding numbers.  Therefore, their answers are somewhat anonymous to encourage students to take risks and participate more freely.  However, I can also assess formatively and discretely since I know which answers belong to each student.  In order not to take time away from my lesson, I take a screen shot of the results and move forward.  I will analyze student data more thoroughly afterwards and have peace of mind knowing that they are well documented.

Students spend time discussing the flip chart in order to clarify the concept of overgeneralization. We begin by discussing that most overgeneralization use words such as all, every, always.  We look at examples and discuss why it is an example of overgeneralization.  The flip chart also shows a video of  a commercial that overgeneralizes to demonstrate that this technique is used in advertisements, newspaper editorials, books, and television shows.  Students will encounter these fallacies in the real world.  I ask students to use examples from every day life that models overgeneralization.  One student said, "My mom says that my room is ALWAYS a mess, but it's not true.  Sometimes it is clean.  So, she is using overgeneralization."  Another student said, "I saw this commercial about a toy that is one of a kind.  The commercial said there was nothing like it in the world.  But, I saw something that looks just like it at the store.  The commercial is not correct.  So, it is using overgeneralization."  Through these discussions, students are applying real experiences into the lesson, just as Common Core learning applies to real world situations.

Hands On Activity

20 minutes

I ask students to work in cooperative groups of four to six members per team and create a flyer that exemplifies overgeneralization.  We review the words: Always, Never, All of them, None of them, Everybody, Nobody, All of the time, None of the time.   These words are exclusive and does not allow for exceptions.  Students can use these words or one of their own to create their Overgeneralization flyer.  As students collaborate, I circulate the classroom to assist and assess their progress. See flip chart source for rules, norms, roles expectations per cooperative team. 

The writing that students are generating are non-examples of the writing standard requiring evidence to support a claim.  By studying non-examples, students develop a deeper understanding of what works and what does not work to substantiate a claim.  Through this type of trial and error, students practice and learn to discriminate effective and ineffective ways to reason.

Critical Analysis

20 minutes

After students completed their project, I ask each group's representative to share their final product.  Then, I ask them to listen to the student audience critique their work.  Students do not receive criticism well, so I explain the purpose of "friendly criticism".  Once students understand that "friendly criticism" is a method to improve their performance, they are more at ease.  However, we follow "friendly criticism" procedures outlined from "The Power of Double Goal Coaching" by Jim Thompson.

The three basic rules to follow from this excerpt:

  1. Ask permission to give the person a "heads up:" "Are you ready for some suggestions?"
  2. If, Then statements: "If you added more details about your product, the audience can better understand why it is so special."
  3. Criticism Sandwich: For each critical remark, precede it with a complementary remark and succeed it with another complementary remark.