Circumference and Area of Circles
Two formulas, one number, infinite depth. Pi (π) is the ratio of every circle's circumference to its diameter — a relationship students can discover by measuring. Once C = πd is understood, A = πr² follows from the same wedge-rearrangement argument used in Grade 6, now applied more formally.
What students explore
Two formulas, one number, infinite depth. Pi (π) is the ratio of every circle's circumference to its diameter — a relationship students can discover by measuring. Once C = πd is understood, A = πr² follows from the same wedge-rearrangement argument used in Grade 6, now applied more formally.
Key ideas
Identify radius, diameter, and circumference and describe their relationships. Calculate circumference using C = π × d. Calculate area using A = π × r². Solve problems involving circles in real-world contexts.
Putting it together
Apply these ideas through hands-on activities, guided practice, and real-world problems.