# Lesson 9

Measure to Find the Area

### Lesson Purpose

The purpose of this lesson is for students to measure side lengths of rectangles to find their area.

### Lesson Narrative

In grade 2, students measured length in centimeters and feet. In earlier lessons, they found the area of rectangles in standard units. Here, students measure side lengths of rectangles and multiply them to find area. They also find side lengths that would result in a rectangle with a given area.

Provide rulers for students to use during the cool-down.

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Find the area of rectangles by measuring and multiplying the side lengths.

### Student Facing

• Let’s measure the sides of rectangles and find the area.

### Required Materials

Materials to Gather

### Required Preparation

Activity 2:

• Each group of 4 will need one roll of either painter's tape or masking tape.

### Lesson Timeline

 Warm-up 10 min Activity 1 15 min Activity 2 20 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

Identify ways the math community you are fostering is going well. What aspects would you like to work on? What actions can you take to improve those areas?

### Suggested Centers

• Capture Squares (1–3), Stage 6: Multiply with 1–5 (Addressing)
• Rectangle Rumble (3–5), Stage 2: Factors 1–5 (Addressing)
• Five in a Row: Addition and Subtraction (1–2), Stage 7: Add within 1,000 without Composing (Supporting)