# 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

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)