Curated OER
Web Math: Find Out Things About Circles
WebMath offers a great site for students to practice finding the diameter, area and circumference of a circle.
Common Core Sheets
Common Core Sheets: Geometry 8.g.3 Worksheets: Coordinate Plane
Worksheets provide practice with finding the area or circumference of a circle and answer keys are provided. You can even create your own worksheet or flashcards.
Calculator Soup
Calculator Soup: Annulus Calculator
This online calculator will find the area, circumference, and radii of an annulus. With any 2 known variables, you can calculate the other 5 unknowns.
Shodor Education Foundation
Shodor Interactivate: Single Fraction Pointer
Determine the value of a given fraction represented as a point on a number line. Then find a fraction whose value is the given fraction using an arrow on the number line as a guide.
PBS
Pbs Learning Media: Square Wheeled Tricycle: Radius and Circumference
This interactive exercise focuses on working with the radius of various circles to find the circumference and area as well as challenging you to find the distance a square wheel travels around the track.
Khan Academy
Khan Academy: Radius and Diameter
Practice finding the radius and diameter of a circle using both vocabulary and visuals. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.