### Lesson plan

# Perimeter of Polygons

#### Learning Objectives

Students will be able to calculate the perimeter of polygons.

#### Introduction

*(2 minutes)*

- Write the word Perimeter on the board.
- Ask students to share what they know and what they want to know about the term. Record their answers on the board around the key term.
- Have students choral read the learning objective. Explain to students that they will be finding the perimeter of different types of polygons.

#### Explicit Instruction/Teacher modeling

*(8 minutes)*

- Explain to students that the
**perimeter**is the distance around a two-dimensional shape that has straight lines. It can be calculated by measuring the length of each side and adding them up. The**length**is how long one side of the shape is. - Teach the process of finding the perimeter of a
**polygon**, an enclosed two-dimensional shape with straight sides. Display a triangle with labeled lengths, and model adding up the lengths to find the perimeter. - Show the Video: Intro to Perimeter for Kids: How to Find the Perimeter of Polygons.

#### Guided Practice

*(10 minutes)*

- Instruct students to debrief about the video in small groups or partnerships. Ask, What do you think is the most important tip from the video for finding perimeter of polygons? Give students time to discuss and share out as a class.
- Establish student partnerships and distribute the Pentagon Perimeters worksheet to each pair.
- Assign each student as an odd number or an even number. The even number partner will complete and think aloud about all even number questions on the worksheet. The odd number partner is responsible for the odd number questions.
- Circulate and monitor students while they work.
- Review student answers by calling on nonvolunteers.

#### Independent working time

*(10 minutes)*

- Distribute the Trapezoid Perimeters worksheet to each student.
- Instruct students to use addition to find the perimeter of each trapezoid.

#### Differentiation

**Support:**

- Intentionally partner students based on academic needs.
- Create a word wall with geometry terms, including visuals, that students can reference when discussing the perimeter of the different shapes. Include the names of shapes, characteristics of shapes, and other key terms, such as perimeter, lengths, sides, and calculate.
- Provide a sentence stem for the closing activity, such as “To find the perimeter of a polygon,
.”**____** - Give students a word bank to use for the closing activity with words such as, length, sides, add, addition, perimeter.

**Enrichment:**

- Provide students with word problems that require them to find the perimeter of a shape. Challenge students to then create their own word problems and have a partner solve them.
- Give students the opportunity to help build a border for a bulletin board. Task them with measuring the length and width of the bulletin board to determine the perimeter. Then, give them the materials to create the border with geometry visuals and key terminology.

#### Assessment

*(5 minutes)*

- Collect the Trapezoid Perimeters worksheet to serve as a formative assessment.
- Give each student an index card for an Exit Ticket.
- Instruct them to draw a rectangular swimming pool that has the lengths of 30 feet on the long sides, and 10 feet on the short sides. Direct students to calculate the perimeter of the swimming pool.

#### Review and closing

*(5 minutes)*

- Have students take out their whiteboards and whiteboard markers.
- Instruct students to write one or two sentences that explain how to find the perimeter of a polygon. Have them include an example with a labeled visual.
- Choose one student to share their answer with the class.