Shape Up! Discovering Perimeter

Mathematics Grades 3rd Grade 4:47 Video
Print Lesson Plan Watch Video

Lesson Description

Learn how to measure the distance around shapes using perimeter! We'll add up all the sides to find the answer.

Video Resource

How to Find Perimeter, Part 1

Miacademy Learning Channel

Duration: 4:47
Watch on YouTube

Key Concepts

  • Perimeter is the distance around a shape.
  • To find the perimeter, add the lengths of all the sides.
  • Shapes can be rectangles, triangles, or other polygons.
  • Sometimes you have to draw a shape from a word problem to find the perimeter.

Learning Objectives

  • Students will be able to define perimeter.
  • Students will be able to calculate the perimeter of a rectangle and a triangle when given the side lengths.
  • Students will be able to draw a rectangle when given the length and width and then find the perimeter.
  • Students will be able to solve word problems involving perimeter.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students if they know what perimeter is. Show the video 'How to Find Perimeter, Part 1' from Miacademy Learning Channel. Explain that perimeter is the distance around a shape, like putting a fence around a yard.
  • Rectangle Perimeter (10 mins)
    Review the rectangle example from the video. Emphasize that opposite sides of a rectangle are equal. Work through another example with the students: a rectangle with a length of 8 cm and a width of 3 cm. Have students add the side lengths together (8 + 8 + 3 + 3 = 22 cm). Remind students to include the units.
  • Triangle Perimeter (10 mins)
    Review the triangle example from the video. Have students find the perimeter of different triangles, e.g., sides of 6 inches, 7 inches, and 8 inches. (6 + 7 + 8 = 21 inches)
  • Word Problem Practice (10 mins)
    Work through the word problem example from the video. Provide students with another word problem: 'A square garden has sides that are 5 feet long. How much fencing do you need to go around the garden?' (Draw a square, label each side 5 feet, and add 5 + 5 + 5 + 5 = 20 feet).
  • Independent Practice (10 mins)
    Give students a worksheet with various shapes (rectangles, triangles) and word problems to solve independently. Circulate to provide support.

Interactive Exercises

  • Shape Scavenger Hunt
    Have students find objects in the classroom or at home that are rectangles or triangles. Have them measure the sides and calculate the perimeter.
  • Perimeter Puzzles
    Give students pre-cut shapes with labeled sides. Have them work in groups to find the perimeters and then match the shapes to their corresponding perimeter values.

Discussion Questions

  • What is perimeter?
  • How do you find the perimeter of a shape?
  • What do you do if only some of the sides of a rectangle are labeled?
  • Why is it helpful to draw a picture when solving perimeter word problems?

Skills Developed

  • Addition
  • Problem-solving
  • Measurement
  • Geometric Reasoning

Multiple Choice Questions

Question 1:

What is perimeter?

Correct Answer: The distance all the way around a shape

Question 2:

How do you find the perimeter of a shape?

Correct Answer: Add all the sides

Question 3:

A rectangle has a length of 7 inches and a width of 3 inches. What is the perimeter?

Correct Answer: 10 inches

Question 4:

A triangle has sides of 4 cm, 5 cm, and 6 cm. What is the perimeter?

Correct Answer: 15 cm

Question 5:

A square has sides of 2 feet each. What is the perimeter?

Correct Answer: 8 feet

Question 6:

If a rectangle has a length of 9 inches, what is the length of the opposite side?

Correct Answer: 9 inches

Question 7:

What shape has 3 sides?

Correct Answer: Triangle

Question 8:

What unit do we use to measure perimeter?

Correct Answer: Inches

Question 9:

What does it mean to draw a picture to help you?

Correct Answer: To help show yourself the shape the question is asking about

Question 10:

What does shape up mean?

Correct Answer: To get ready to measure shapes

Fill in the Blank Questions

Question 1:

Perimeter is the distance all the way _______ a shape.

Correct Answer: around

Question 2:

To find the perimeter, you need to ______ all the sides of a shape.

Correct Answer: add

Question 3:

If a rectangle has a length of 5 feet and a width of 2 feet, the perimeter is ______ feet.

Correct Answer: 14

Question 4:

A triangle with all equal sides that measure 3 cm each has a perimeter of ______ cm.

Correct Answer: 9

Question 5:

If you are only given some side lengths, and you need to find perimeter of a square or rectangle, you should ______ the missing side length.

Correct Answer: label

Question 6:

In order to learn the perimeter of a shape from a word problem, what should you do?

Correct Answer: draw a picture

Question 7:

A shape with opposite sides that are even is called a ______.

Correct Answer: rectangle

Question 8:

A shape with three sides is called a ______.

Correct Answer: triangle

Question 9:

A shape where all the sides have the same length and all angles are 90 degrees is called a ______.

Correct Answer: square

Question 10:

When adding side lengths, it is important to use the same ______.

Correct Answer: units

Educational Standards

3.GM.2.1:Find the perimeter of a polygon, given whole number lengths of the sides, using a variety of models. 3.N.2.3:Use strategies and algorithms based on knowledge of place value and equality to fluently add and subtract up to five-digit numbers (answer not to exceed 100,000). 3.GM.1:Analyze and use geometric attributes to describe and create polygons and three-dimensional figures in various contexts.

Teaching Materials

Download ready-to-use materials for this lesson:

Student Worksheet Classroom Slides Assessment Quiz
Add to Google Classroom

User Actions

Sign in to save this lesson plan to your favorites.

Sign In

Share This Lesson

Related Lesson Plans