1
Slide 1
Circle Formulas: Circumference and Area
Grade 7 Mathematics 15-minute lesson
Slide 2
Hook: What Are We Measuring?
Look at this circular plate String around the edge = ? Space it covers on table = ?
Slide 3
Key Terms: Circumference and Area
Circumference: Distance around the circle Area: Space inside the circle Both use the special number π (pi)
Slide 4
Circle Formulas
Slide 5
Example: Circle with Radius 3
Given: radius = 3 units Circumference: C = 2π × 3 = 6π ≈ 18.85 Area: A = π × 3² = 9π ≈ 28.27
Slide 6
Think About It: How Are They Connected?
Use your mini whiteboard How do you think circumference and area formulas relate? Write your thoughts or draw a connection
7
Slide 7
Quick Practice
Problem 1: Find circumference when diameter = 10 units Problem 2: Find area when radius = 5 units Work it out, then share your answer!
Slide 8
Key Takeaways
Circumference: C = 2πr or C = πd Area: A = πr² π ≈ 3.14 (but leave as π for exact answers) Circumference measures around, area measures inside