Khan Academy
Khan Academy: Area and Circumference of Circles Challenge
Practice interesting area and circumference problems. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Cuemath
Cuemath: Area of a Circle
This mini-lesson explores the area of a circle. Provides a definition, examples, and practice questions with answers.
CK-12 Foundation
Ck 12: Geometry: Circumference and Arc Length Study Guide
This study guide on circumference and arc length covers key vocabulary, the parts of a circle, and formulas for circumference, area, and arc length. It is available for download with free registration.
Khan Academy
Khan Academy: Circumference of a Circle
Find the circumference of a circle when given either the radius or diameter.Find the radius or diameter of a circle when given the circumference.Students receive immediate feedback and have the opportunity to try questions repeatedly,...
National Council of Teachers of Mathematics
The Math Forum: Elementary Geometry Circles
The Math Forum offers an archive of question and answer sessions on circles and how they relate to geometry.
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.