Lesson Plan


Students look at two triangles and must prove whether one line is longer than another. The results are surprising, and there are many different ways to prove the answer to be true.


  • Mathematics > General
  • Mathematics > Geometry

Education Levels:

  • Grade 6
  • Grade 7
  • Grade 8
  • Grade 9
  • Grade 10
  • Grade 11
  • Grade 12


geometry measurement coordinate conjecture pythagorean theorum trapezoid



Access Privileges:

Public - Available to anyone

License Deed:

Creative Commons Attribution 3.0


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Curriki Rating
On a scale of 0 to 3
On a scale of 0 to 3

This resource was reviewed using the Curriki Review rubric and received an overall Curriki Review System rating of 3, as of 2009-07-26.

Component Ratings:

Technical Completeness: 3
Content Accuracy: 3
Appropriate Pedagogy: 3

Reviewer Comments:

As the commenter points out., students may think of this problem as a puzzle. The result is unexpected but of course inevitable. The author solves this problem different ways, whichj gives real insight into the solution.
sarahmcclellan sarahbethmcclellan
April 13, 2009

This is a great way to encourage students to use critical thinking. Students may think of this type of work as a puzzle more than an assignment.

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