# Geometry: Formal Logic:Proving Conjectures False - Class Activity

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0.78 MB   |   3 pages

### PRODUCT DESCRIPTION

Are your students struggling with the concept of counter-examples? Are you teaching Geometry for the first time? Coming up with great true and false statements can be confusing. Use this worksheet to help you introduce formal logic into your class. This printable worksheet contains 20 statements that your students will have to label as true or false. If they are false they must provide a valid counter-example. This can get tricky because some students don't realize that the counter-examples must have a format of their own. Here is an example of what the problems are like on the worksheet:

1. All teachers are blonde.

This is obviously a FALSE statement. A good counter-example would be to list a teacher that you know who IS a teacher but is not blonde. This teacher could have red hair for example.

A bad counter-example would be to say "Taylor Swift is Blonde and she is not a teacher."

A true counter-example must be one where the hypothesis, or first part must still be true, but you prove the conclusion to be false.

As I have mentored new teachers and student teachers I have found that even some of the adults miss this slight difference in language and lead the students in the wrong direction. This worksheet will make it clear for everyone.

Some of the questions will require students to interact with each other and others might require them to look up information. I have received a lot of positive feedback from my class about this activity.

If you are pleased with this activity I would appreciate any positive feedback you would be willing to leave. Happy Teaching!

(Check back often for updated Geometry and Algebra resources.)

Total Pages
3
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Teaching Duration
40 Minutes

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