4.3 - Finding the Area of Polygons

7th Grade Math

Unit 4, Lesson 3

Finding the Area of

Polygons

Volume 1, pg. 136

Benchmark

volume 1, pg. 136

MA.7.GR.1.2

Solve mathematical or real–world problems
involving the area of polygons or composite
figures by decomposing them into triangles
or quadrilaterals.

Integrated Mathematical Thinking and
Reasoning Standards

volume 1, pg. 136

MA.K12.MTR.1.1 Actively participate in effortful learning both
individually and collectively.

MA.K12.MTR.2.1 Demonstrate understanding by representing
problems in multiple ways.

MA.K12.MTR.4.1 Engage in discussions that reflect on the
mathematical thinking of self and others.

MA.K12.MTR.5.1 Use patterns and structure to help understand
and connect mathematical concepts.

Learning Targets

volume 1, pg. 136

❑ I can decompose a regular polygon into

triangles to find the area.

❑ I can decompose a regular polygon into

triangles and quadrilaterals to find the
area.

Warm-Up

volume 1, pg. 137

Draw

Draw a line to identify the number of triangles.

Draw

Instruction:

a. Put a dot in the center.

b. Draw as many equal triangles within the pentagon.

Draw

Instruction:

a. Put a dot in the center.

b. Draw as many equal triangles within the pentagon.

Draw

Instruction:

a. Put a dot in the center.

b. Draw as many equal triangles within the pentagon.

Open Ended

How would decomposing [breaking down]

the shapes into equal triangles helpful in finding the area?

Learning Targets

volume 1, pg. 136

❑ I can decompose a regular polygon into

triangles to find the area.

❑ I can decompose a regular polygon into

triangles and quadrilaterals to find the
area.