# 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.

Building Towards

### Lesson Timeline

 Warm-up 10 min Activity 1 20 min Activity 2 15 min Lesson Synthesis 10 min Cool-down 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)