Lesson 14
Find the Area of Figures with Missing Sides
Lesson Purpose
The purpose of this lesson is for students to calculate the area of ungridded figures made of rectangles, including figures with missing side lengths.
Lesson Narrative
In previous lessons, students found the area of figures that were fully gridded with squares and moved toward figures without a grid but had all their side lengths labeled. In this lesson, students use the strategies they have learned to decompose the figures into non-overlapping rectangles. They realize that not all measurements need to be given, and that some lengths can be determined given the rectangular structure of these figures.
- Engagement
- MLR8
Learning Goals
Teacher Facing
- Calculate the area of ungridded figures composed of rectangles, including figures with missing side lengths.
Student Facing
- Let’s find the area of figures with missing side lengths.
Required Preparation
CCSS Standards
Addressing
Lesson Timeline
| Warm-up | 10 min |
| Activity 1 | 10 min |
| Activity 2 | 25 min |
| Lesson Synthesis | 10 min |
| Cool-down | 5 min |
Teacher Reflection Questions
Reflect on which students have not shared their strategies in class lately. How can their insight or ways of thinking be highlighted in or tied to upcoming lessons?
Suggested Centers
- Five in a Row: Multiplication (3–5), Stage 2: Factors 1–9 (Addressing)
- Five in a Row: Addition and Subtraction (1–2), Stage 8: Add within 1,000 with Composing (Supporting)