Curated OER
Parametric Unit Circle
This site provides definitions for different parts of a circle, pictures to more clearly represent formulas involving circles. Some of the formulas discussed include: area of a circle, area of a sector of a cirles, circumference, length...
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.
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Circunferencia Y Circulo: Longitudes Y Areas
Reinforce your knowledge of the circumference and the area of a circle with these activities. [Requires Java.]
Texas A&M University
Wtamu Virtual Math Lab: Beginning Algebra: Formulas
This tutorial will show you how using formulas can help you solve problems. Include formulas for various geometric shapes and steps showing how to use them.
Other
Allmath: Math Glossary
Are your students having difficulty understanding math terminology? Try this A-Z glossary on math related terms. It's quick, easy to read, and very complete.
Khan Academy
Khan Academy: Radius and Diameter
Practice problems finding radius and diameter of a circle.
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Geometry in the Plane
Twenty-four problems presented on a variety of Plane Geometry topics. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the "View Solution" button to check...
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.
Alabama Learning Exchange
Alex: Circling Around
Learners will calculate the diameter, circumference, and ratio of a real world object. Students will create an electronic slideshow to illustrate the process of determining the diameter, circumference, and ratio of these objects.
Cuemath
Cuemath: Radius
This reference tool explores the radius of a circle. Provides definitions, solved examples, and practice questions with answers.
Cool Math
Coolmath: Precalculus Basic Formulas to Know
This CoolMath resource provides an introduction to some Precalculus formulas.
Math Open Reference
Math Open Reference: Diameter
A complete reference guide to diameters. It provides definitions, examples, and interactive activities that enhance further explanation. Includes links to related topics.
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.
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.
National Council of Teachers of Mathematics
The Math Forum: Multicultural Math Fair: Srinivasa's Spheres
Straightforward lesson that introduces learners to pi by letting them measure real objects and solve a challenge problem. Includes instructions and a "Data Sheet" for keeping track of measurements. Available in English and Spanish.