Lesson 8

The purpose of this lesson is for students to classify triangles using angle measures and side lengths.

The purpose of this lesson is to sort triangles into categories, recognizing right triangles as a category. Students also examine side lengths and notice that sometimes all 3 side lengths are different, sometimes 2 side lengths are equal, and sometimes all 3 side lengths are equal. Students identify right triangles and examine the possible angles that a triangle can have. For example, there are triangles with 3 acute angles but a triangle can only have one right or obtuse angle. Students should have access to straight edges, protractors, and patty paper throughout this lesson.

• Create a set of cards from the blackline master for each group of 2. 

• Gather materials from previous activity:
  • Triangle Cards

How are students applying what they learned about the hierarchy of quadrilaterals to help them make sense of classifying triangles?