Lesson 5
Trapezoids
Lesson Purpose
The purpose of this lesson is for students to explore two different definitions of trapezoid.
Lesson Narrative
The purpose of this lesson is for students to explore trapezoids and agree on a definition of trapezoids for this course. In the first activity, students see two different definitions for a trapezoid both of which are commonly used, one that excludes parallelograms and one that includes parallelograms. The exclusive definition of a trapezoid states that a trapezoid has exactly one pair of opposite sides that are parallel. The inclusive definition states that a trapezoid has at least one pair of opposite sides that are parallel. In the second activity, students recognize that we have chosen to use the inclusive definition of a trapezoid. Students should have access to straight edges, protractors, and patty paper throughout this lesson.
 Engagement
 MLR8
Activity 1: What’s a Trapezoid?
Learning Goals
Teacher Facing
 Compare different definitions for trapezoids, and use them to identify trapezoids.
Student Facing
 Let’s explore trapezoids.
Required Preparation
Lesson Timeline
Warmup  10 min 
Activity 1  20 min 
Activity 2  15 min 
Lesson Synthesis  10 min 
Cooldown  5 min 
Teacher Reflection Questions
Did students notice the difference in the definitions of the trapezoid? How did they explain that difference in terms of the hierarchy on the anchor chart?
Suggested Centers
 Can You Draw It? (1–5), Stage 6: Shapes on the Coordinate Grid (Addressing)
 Which One? (K–5), Stage 6: Shapes on the Coordinate Grid (Addressing)
 How Are They the Same? (1–5), Stage 4: Grade 4 Shapes (Supporting)
Print Formatted Materials
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Additional Resources
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