Grade 7 · Math · Unit 10 of 14

Circles

Circumference, area and π

What your child practises

Using radius, diameter and π (about 3.14) to find the distance around a circle and the area inside it, including real objects like wheels and pizzas.

Nova Scotia Curriculum learning outcome: M01 · circumference and the relationship to diameter

Children can open this short lesson before they practise.

The radius goes from the centre to the edge. The diameter goes all the way across: d = 2r.
Circumference (the distance around) is C = π × d.
Area is A = π × r × r. Use π ≈ 3.14.

Example: A circle has diameter 10 cm. What is its circumference? C = π × d. C ≈ 3.14 × 10 = 31.4. Answer: About 31.4 cm

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

Question 1
A circle has a diameter of 32 cm. What is its circumference? Use 3.14 for π and round to one decimal place.
⭕d = 32 cm
answer boxcm
Question 2
A circle has a radius of 11 cm. What is its area? Use 3.14 for π and round to one decimal place.
⭕r = 11 cm
answer boxcm²
Question 3
A circle has a radius of 24 cm. What is its diameter?
⭕r = 24 cm
- 12 cm
- 96 cm
- 48 cm
- 24 cm
Question 4
A circle has a radius of 23 m. What is its circumference? Use 3.14 for π and round to one decimal place.
⭕r = 23 m
answer boxm
Question 5
A circle's circumference is 37.68 cm. What is its diameter? (Use 3.14 for π.)
answer boxcm
Question 6
A circle has a diameter of 28 cm. Using 3.14 for π, what is its area?
⭕d = 28 cm
- 87.92 cm²
- 2461.76 cm²
- 615.44 cm²
- 43.96 cm²