Year 4 Maths: Perimeter

What is Perimeter?

Hello, Year 4! Today, we’re going to learn about perimeter. Perimeter is the total distance around the outside of a shape. Imagine if you were walking around a playground; the distance you walk to get back to where you started is the perimeter!

Key Rules

1. What Shapes Have Perimeters?
   • Perimeter can be found for many shapes like squares, rectangles, triangles, and circles.
2. How to Calculate Perimeter?
   • For rectangles: Add the lengths of all four sides. If the length is $$l$$ and the width is $$w$$ , the formula is: $$P = 2l + 2w$$
   • For squares: Since all sides are the same, if one side is $$s$$ , the formula is: $$P = 4s$$
   • For triangles: Add up the lengths of all three sides. If the sides are $$a$$ , $$b$$ , and $$c$$ , the formula is: $$P = a + b + c$$
3. Units of Measurement
   • We often measure perimeter in centimetres (cm) or metres (m).

Tips and Tricks

• Draw It Out: If you can, draw the shape. This can help you see where to measure.
• Use a Ruler: If the shape is not given in numbers, use a ruler to measure each side.
• Remember to Add: Always make sure you add all the sides together to find the total.

Quick Examples

1. Rectangle Example:
   • Length = 5 cm, Width = 3 cm
   • $$P = 2(5) + 2(3) = 10 + 6 = 16 \text{ cm}$$
2. Square Example:
   • Side = 4 cm
   • $$P = 4(4) = 16 \text{ cm}$$
3. Triangle Example:
   • Sides = 3 cm, 4 cm, and 5 cm
   • $$P = 3 + 4 + 5 = 12 \text{ cm}$$

Questions

Easy Level Questions

1. What is the perimeter of a square with sides of 2 cm?
2. If a rectangle has a length of 3 cm and a width of 2 cm, what is its perimeter?
3. A triangle has sides of 3 cm, 3 cm, and 4 cm. What is its perimeter?
4. What is the perimeter of a square with a side length of 5 cm?
5. If a rectangle has a length of 6 cm and a width of 1 cm, what is its perimeter?
6. A triangle has sides of 2 cm, 2 cm, and 3 cm. What is its perimeter?
7. What is the perimeter of a square with a side length of 10 cm?
8. A rectangle has a length of 7 cm and a width of 3 cm. What is its perimeter?
9. If all sides of a square are 6 cm, what is the perimeter?
10. A triangle has sides of 5 cm, 5 cm, and 5 cm. What is its perimeter?

Medium Level Questions

1. Calculate the perimeter of a rectangle with a length of 8 cm and a width of 5 cm.
2. What is the perimeter of a square with a side length of 4 m?
3. A triangle has sides of 5 m, 7 m, and 9 m. What is its perimeter?
4. Find the perimeter of a rectangle with a length of 10 cm and a width of 4 cm.
5. If a square has a perimeter of 32 cm, what is the length of one side?
6. A rectangle has a length of 12 m and a width of 3 m. What is its perimeter?
7. Calculate the perimeter of a triangle with sides of 6 cm, 8 cm, and 10 cm.
8. If one side of a square is 3 m, what is the perimeter?
9. A rectangle has a perimeter of 30 cm and a length of 10 cm. What is the width?
10. Find the perimeter of a triangle with sides measuring 4 cm, 5 cm, and 6 cm.

Hard Level Questions

1. A rectangle has a length of 14 cm and a width of 6 cm. What is its perimeter?
2. If a square has a side length of 12 cm, what is the perimeter?
3. A triangle has sides of 10 cm, 15 cm, and 20 cm. What is its perimeter?
4. A rectangular garden has a length of 13 m and a width of 9 m. What is the perimeter?
5. A square has a perimeter of 40 cm. What is the length of one side?
6. Calculate the perimeter of a triangle with sides of 8 cm, 15 cm, and 17 cm.
7. A rectangle has a length of 20 cm and a width of 10 cm. What is its perimeter?
8. Find the perimeter of a square with a side length of 8 m.
9. A triangle has a perimeter of 30 cm and two sides of 10 cm each. What is the length of the third side?
10. If a rectangle has a perimeter of 50 cm and a length of 20 cm, what is its width?

Answers

Easy Level Answers

1. 8 cm
2. 10 cm
3. 10 cm
4. 20 cm
5. 14 cm
6. 7 cm
7. 40 cm
8. 20 cm
9. 24 cm
10. 15 cm

Medium Level Answers

1. 26 cm
2. 16 m
3. 21 m
4. 28 cm
5. 8 cm
6. 30 m
7. 24 cm
8. 12 m
9. 5 cm
10. 15 cm

Hard Level Answers

1. 40 cm
2. 48 cm
3. 45 cm
4. 44 m
5. 10 cm
6. 40 cm
7. 60 cm
8. 32 m
9. 10 cm
10. 5 cm

I hope you enjoyed learning about perimeter! Keep practicing, and soon you’ll be a perimeter pro!