Lesson Notes By Weeks and Term v5 - Grade 3
Measurement: perimeter, area (counting squares) and volume (intro) – Week 3 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Measurement: perimeter, area (counting squares) and volume (intro) – Week 3 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Mathematics
Class: Grade 3
Term: 3rd Term
Week: 3
Theme: General lesson support
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
Welcome Grade 3 learners! This week, we're going to become measurement masters! We will be exploring perimeter, area, and getting a sneak peek at volume. Measurement is incredibly important in our everyday lives. Imagine helping your family build a veggie garden or putting up a fence to keep the goats in. You need to know how much space you have and how much material you'll need. Think about putting a tablecloth on a table or knowing how much juice will fit in your jug. These are all examples of when measurement helps us! This week, we’ll learn the basics, which will help you solve these real-world problems and more!
Let’s explore our measuring world!
Perimeter: Perimeter is the total distance around the outside of a shape. Think of it like walking around the edge of your school's soccer field. The total distance you walk is the perimeter. To find the perimeter, we simply add up the lengths of all the sides of the shape.
Example: Imagine a rectangular vegetable patch. One side is 5 meters long, and the other side is 3 meters long.
To find the perimeter: Side 1: 5 meters Side 2: 3 meters Side 3: 5 meters (because rectangles have two sides of the same length)
Side 4: 3 meters (because rectangles have two sides of the same length) Perimeter = 5 + 3 + 5 + 3 = 16 meters. We need 16 meters of fencing to go around the vegetable patch! Another
Example: A square has all four sides the same length. If one side of a square is 4 cm, then the perimeter is 4 + 4 + 4 + 4 = 16 cm.
Area: Area is the amount of space a flat (2D) shape covers. Imagine painting a wall – the area is the amount of wall you need to paint. We usually measure area by counting squares. We'll use grid paper (paper with lots of squares) to help us.
Example: Imagine a small garden bed made of paving stones. It is 3 squares long and 2 squares wide on our grid paper.
To find the area: We can count the squares inside the shape: 1, 2, 3, 4, 5,
6. There are 6 squares. So, the area is 6 square units. If each square was 1 meter by 1 meter, then the area would be 6 square meters. Important
Note: We say "square units" because we are counting squares! Perimeter vs.
Area: Perimeter is the distance around a shape (like a fence), and area is the space inside the shape (like the grass inside the fence). They are different things!
Volume (Introduction): Volume is the amount of space something takes up. It's for 3D (three-dimensional) objects. Think about filling a jug with juice. The volume is the amount of juice that fits inside the jug. We won't be calculating volumes accurately this week, but we'll start to understand what it means.
Example: A small box takes up less space than a big box. The big box has a larger volume.
Estimating Volume: We can compare two containers and try to guess which one holds more. A tall, thin bottle might look like it holds more than a short, wide container, but that's not always true! A short, wide bucket can hold more water than a tall, thin vase. We can compare by pouring water from one container into another to see if it overflows or if there's space left over. Guided Practice (With Solutions)
Question 1: A rectangular picture frame has a length of 10 cm and a width of 5 cm. What is the perimeter of the picture frame?
Solution: Perimeter = side 1 + side 2 + side 3 + side 4 Perimeter = 10 cm + 5 cm + 10 cm + 5 cm Perimeter = 30 cm Explanation: We added up the lengths of all four sides of the rectangle. Remember, rectangles have two pairs of equal sides.
Question 2: A square tile has a side length of 3 cm. What is the area of the tile? (Use grid paper if available).
Solution: Imagine a square drawn on grid paper with each side measuring 3 squares. Count the squares inside. There are 9 squares. Area = 9 square cm Explanation: We counted the number of squares that fit inside the tile. Since it's a square, all sides are the same length.
Question 3: Which has a larger perimeter: a square with sides of 2 meters each or a rectangle with length of 3 meters and width of 1 meter?
Solution: Square perimeter: 2m + 2m + 2m + 2m = 8 meters Rectangle perimeter: 3m + 1m + 3m + 1m = 8 meters They have the same perimeter!
Explanation: We calculated the perimeter of each shape and compared the answers.
Question 4: You have two buckets. One is tall and thin, and the other is short and wide. Which one do you think can hold more water? Why?
Solution: This is an estimation question. There is no single right answer. Encourage the child to experiment. It will likely be the short and wide bucket.
Explanation: Volume is the amount of space something takes up. Independent Practice (Questions Only) A rectangular garden is 8 meters long and 4 meters wide. What is the perimeter of the garden? A square tablecloth has a side length of 2 meters. What is the area of the tablecloth? Draw a rectangle on grid paper that has an area of 12 square units. A classroom floor is made of square tiles. Each tile is 1 meter by 1 meter. The floor is 6 tiles long and 5 tiles wide. What is the area of the classroom floor?
You have two containers: a glass and a jug. Which one do you think holds more juice? How could you check? A square playground has sides of 10 meters each. What is the perimeter of the playground? A farmer wants to put a fence around a rectangular field. The field is 15 meters long and 7 meters wide. How much fencing does the farmer need? Draw two different rectangles on grid paper, both with a perimeter of 20 units. What are their areas? You have a small box and a large suitcase. Which has a larger volume? Name 3 things you might measure the perimeter of at your home.