Peter Weatherall: Circle Song
Peter Weatherall

Learn about the geometry of circles with Peter Weatherall’s Circle Song.

Mathalicious: Pizza Pi (HS)
Mathalicious

In this lesson, students use the formula for the area of a circle to calculate how much of a pizza is actually pizza, and how much is crust.

Illuminations: Discovering the Area Formula for Circles
Illuminations (National Council of Teachers of Mathematics)

Using a circle that has been divided into congruent sectors, students will discover the area formula by using their knowledge of parallelograms.

GeoGebra: Estimating Areas - IM 7.3.6
GeoGebra

“Estimating Areas” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Relating Area to Circumference - IM 7.3.8
GeoGebra

“Relating Area to Circumference” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Stained-Glass Windows - IM 7.3.11
GeoGebra

“Stained-Glass Windows” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Slopes Don't Have to be Positive IM 8.3.9
GeoGebra

“Slopes Don’t Have to be Positive” from IM Grade 8 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Applying Area of Circles IM 7.3.9
GeoGebra

“Applying Area of Circles” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Exploring Circles IM 7.3.2
GeoGebra

“Exploring Circles” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Applying Circumference: IM 7.3.4
GeoGebra

“Applying Circumference” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Distinguishing Circumference and Area IM 7.3.10
GeoGebra

“Distinguishing Circumference and Area” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.

GeoGebra: Circumference and Wheels IM 7.3.5
GeoGebra

“Circumference and Wheels” from IM Grade 7 by Open Up Resources and Illustrative Mathematics.