Lesson objective: Reason about the size of different square units to solve area problems.

This lesson provides an opportunity for students to apply their knowledge and understanding of measuring area using different square units (square inches, square centimeters, square feet, square meters) to a real-life situation. Students are asked to analyze the numbers for screen area on an electronics sale flyer, to decide whether the numbers are reasonable for the size of a TV and two smartphones.

Key Concept students will use:

- square units or unit squares (that cover a figure without gaps) can be used to measure the area of a figure, which is said to be n square units

Skills students will use:

- count square units to determine the area of a rectangle
- use different sizes of square units to compare area measurements
- create an array for a fixed number of square tiles (Grade 2, Unit 13)

Students engage in Mathematical Practice 2 (reason abstractly and quantitatively) as they apply their knowledge of the size of different square units to make sense of the area measurements listed in the electronics flyer. Students also engage in Mathematical Practice 6 (attend to precision) as they use different square units to give meaning to the numbers representing screen area measurements.

**Key vocabulary: **

- area
- square centimeter
- square foot
- square inch
- square meter
- square unit

**Special materials needed:**

- centimeter graph paper or tiles
- construction paper and scissors to cut out square feet "tiles" (you may want to provide templates for students to trace around, or cut out several paper square feet in advance for students to use)
- inch graph paper or tiles