🔍 Part 1: Circle Parts and Vocabulary

1. Label the parts of the circle below. Use the words: radius, diameter, centre, circumference

2. Fill in the blanks using mathematical vocabulary:

The ____________ is the distance from the centre to the edge of a circle.

The ____________ is twice the length of the radius.

The ____________ is the distance around the outside of a circle.

3. Circle the correct relationship:

Diameter = radius ÷ 2

Diameter = radius × 2

Diameter = radius + 2

📐 Part 2: Area Formula and Basic Calculations

4. The formula for the area of a circle is:

5. Calculate the area of a circle with radius = 5 cm. Show all your working and include units. Use π ≈ 3.14

6. Calculate the area of a circle with radius = 8 cm. Show all your working and include units.

7. A circle has a radius of 3 metres. What is its area in square metres?

🔄 Part 3: Converting Diameter to Radius

8. A circle has a diameter of 12 cm. First find the radius, then calculate the area.

Step 1: Find the radius: ____________ cm

Step 2: Calculate the area:

9. Complete the table by finding the radius and area for each circle:

Diameter = 10 cm, Radius = _____ cm, Area = _____ cm²

Diameter = 16 m, Radius = _____ m, Area = _____ m²

Diameter = 20 cm, Radius = _____ cm, Area = _____ cm²

10. Explain in your own words why we need to convert diameter to radius before using the area formula:

🌟 Part 4: Extension Challenge Problems

11. Calculate the area of a circle with radius = 2.5 cm. Show all working.

12. A circle has a diameter of 7.2 metres. Find its area to 2 decimal places.

13. Challenge: A circle has a radius of 1½ cm. Calculate its area. (Hint: Convert the mixed number to a decimal first)

14. Real-life application: A circular garden has a diameter of 6 metres. If grass seed costs $8 per square metre, how much will it cost to seed the entire garden?

💭 Part 5: Reasoning and Reflection

15. Two circles have the same centre. Circle A has radius 4 cm and Circle B has radius 8 cm. How many times larger is the area of Circle B compared to Circle A? Explain your reasoning using mathematical vocabulary.

16. Describe one real-life situation where you might need to calculate the area of a circle:

17. What was the most challenging part of calculating circle areas today? How did you overcome this challenge?