Lesson Notes By Weeks and Term v5 - Grade 3

Lesson Video

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Performance objectives

• This week, we're diving into the world of Measurement! We'll be exploring perimeter, area (by counting squares), and getting a sneak peek at what volume is all about. Measurement is super important because it helps us understand the world around us. Think about it: when you're helping your family plant vegetables in the garden, you need to know how much space each plant needs (area). When you're putting up a fence around the garden to keep the chickens out, you need to know how much fencing to buy (perimeter). And when you're filling up a watering can, you're dealing with volume (though we'll just introduce this concept this week!). These skills will help you in everyday life, from cooking and building to planning and understanding the world around you.
• By the end of this week, you will be able to:
• Define perimeter and calculate the perimeter of simple shapes by measuring and adding the lengths of their sides.
• Determine the area of simple shapes by counting squares.
• Distinguish between perimeter and area.

Lesson summary

This week, we're diving into the world of Measurement! We'll be exploring perimeter, area (by counting squares), and getting a sneak peek at what volume is all about. Measurement is super important because it helps us understand the world around us.

Think about it: when you're helping your family plant vegetables in the garden, you need to know how much space each plant needs (area). When you're putting up a fence around the garden to keep the chickens out, you need to know how much fencing to buy (perimeter). And when you're filling up a watering can, you're dealing with volume (though we'll just introduce this concept this week!).

Lesson notes

2.1 Perimeter What is Perimeter? The perimeter is the total distance around the outside of a shape. Imagine you're walking all the way around your school's playground – the total distance you walk is the perimeter of the playground! We find perimeter by adding up the length of all the sides of the shape.

How to Calculate Perimeter: Measure: Use a ruler (if available) or count the units of length along each side of the shape.

Add: Add up all the lengths you measured. The total is the perimeter!

Units: We use units like centimetres (cm), metres (m), or even just "units" if we're counting squares on a grid.

Example 1: Imagine a rectangular garden bed. One side is 3 metres long, and the other side is 2 metres long. Since it's a rectangle, the opposite sides are equal. So we have two sides that are 3 metres each, and two sides that are 2 metres each. To find the perimeter, we add them all up: 3m + 2m + 3m + 2m = 10m. The perimeter of the garden bed is 10 metres.

Example 2: Consider a triangle with sides of 4cm, 5cm, and 6cm. To find the perimeter, we simply add the lengths of the sides: 4cm + 5cm + 6cm = 15cm. The perimeter of the triangle is 15cm.

Example 3: A square has all four sides equal. If one side of a square is 5cm, what is the perimeter? Since all sides are equal, each side is 5cm. So the perimeter is 5cm + 5cm + 5cm + 5cm = 20cm. 2.2 Area (Counting Squares) What is Area? Area is the amount of space a shape covers. Imagine you're tiling the floor of your bedroom – the area is how much floor you need to cover with tiles. We measure area in square units.

Counting Squares: The easiest way to find the area of a shape (especially in Grade 3) is to count the number of squares that fit inside it. Each square has an area of 1 square unit.

Units: We use units like square centimetres (cm²) or square metres (m²) or just "square units".

Example 1: Draw a rectangle on grid paper that is 4 squares long and 3 squares wide. To find the area, count the number of squares inside the rectangle. You'll find there are 12 squares. So the area of the rectangle is 12 square units.

Example 2: Draw an irregular shape on grid paper (like a cloud). Count the squares inside the shape. If some squares are only partially inside, you can estimate by combining partial squares to make whole squares. This will give you an approximate area.

Example 3: Imagine a small carpet in your living room is made up of 20 squares. If each square is 1 meter by 1 meter, then the area of the carpet is 20 square meters (20 m²). 2.3 Volume (Introduction) What is Volume? Volume is the amount of space something takes up. Think about filling a jug with juice. The volume is the amount of juice the jug can hold. We usually talk about volume with things that can be poured, like liquids, but even a solid object like a stone has volume.

Relating to Containers: The volume of a container is how much it can hold. We can compare the volume of different containers by filling them with something like sand or water and seeing which one holds more.

Non-Standard Units: For now, we'll use non-standard units to measure volume. This means we'll use things like spoons, cups, or scoops to fill containers.

Example 1: You have two glasses, a small one and a big one. You fill the small glass with water and pour it into a jug. You do this 5 times to fill the jug. Then, you fill the big glass with water and pour it into the same jug. You only need to do this 3 times to fill the jug. This shows that the big glass has a larger volume than the small glass.

Example 2: You have two buckets. You use a small scoop to fill each bucket with sand. You need 20 scoops to fill the first bucket, and 30 scoops to fill the second bucket. This shows that the second bucket has a larger volume than the first bucket. Guided Practice (With Solutions)

Question 1: A farmer wants to build a fence around his chicken coop. The chicken coop is a rectangle with sides of 6 metres and 4 metres. How much fencing does he need to buy?

Solution: This is a perimeter problem. We need to find the total distance around the chicken coop. Perimeter = 6m + 4m + 6m + 4m = 20m. The farmer needs to buy 20 metres of fencing.

Commentary: We correctly identified this as a perimeter problem and added all the sides.

Question 2: A square patio is covered with square tiles. Each side of the patio has 5 tiles. What is the area of the patio in square tiles?

Solution: The area is the number of tiles covering the patio. Since it's a square with 5 tiles on each side, there are 5 rows of 5 tiles. So the area is 5 x 5 = 25 square tiles. The area of the patio is 25 square tiles.

Commentary: We correctly counted the square units, recognizing the relationship between the sides.

Question 3: You have a small teacup and a larger mug. You use a spoon to fill each one with water. It takes 8 spoons of water to fill the teacup and 15 spoons of water to fill the mug. Which container has a larger volume?