How Many Triangles?

This How Many Triangles? lesson plan also includes:

Something for young mathematicians to remember: the sum of any two sides must be greater than the third. Class members investigates the Triangle Inequality Theorem to find the relationship between the sides of a triangle. At the same time, they collect data to develop the relationship between the sizes of the angles of a triangle and the lengths of its sides.

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CCSS: Adaptable
Instructional Ideas

  • Use geometry software to create triangles that can be manipulated to find the range of possible lengths of a third side
Classroom Considerations

  • Class members should know the sum of the angles of a triangle is 180
  • Requires the use of pipe cleaners or narrow strips of paper that are a foot in length
Pros

  • Contains a variety of assessment questions and tasks
  • Includes strategies for differentiation
Cons

  • None
Common Core