Lesson plan

3. Classify triangles (FP)

teaches Common Core State Standards CCSS.Math.Content.5.G.B.3 http://corestandards.org/Math/Content/5/G/B/3
teaches Common Core State Standards CCSS.Math.Content.5.G.B.4 http://corestandards.org/Math/Content/5/G/B/4
teaches Common Core State Standards CCSS.Math.Practice.MP7 http://corestandards.org/Math/Practice/MP7

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Lesson objective: Classify triangles by the lengths of their sides.

This lesson helps to build fluency with classifying two-dimensional figures. Triangles are used here because they support students' understanding that two-dimensional figures can be classified by different attributes. This work develops students' understanding that objects have geometric properties that allow us to create categories of objects.

Students engage in Mathematical Practice 7 (look for and make use of structure) as they create organized structures for categories of shapes to visualize the relationships between different plane figures.  

Key vocabulary:

  • acute
  • attribute
  • equilateral
  • isosceles
  • obtuse
  • right angle
  • scalene