Find the area of a circle given its radius, diameter, or circumference. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

Practice finding the circumference of a circle.

Definition of circumference. Click the "here's more" link to learn more about a circle; its radius and diameter, area, lines, slices and common sectors.

Circle Geometry math for kids contains information for students to learn about terms radius, diameter, circumference, chord, and pi.

Various forms of equations of circles are presented at the Math Forum: center-radius form, general form, diameter form, three-point form, and parametric form.

Students will play an interactive game to identify the circumference, radius, center, and diameter of circles.

[Free Registration/Login may be required to access all resource tools.] Identify pi as the ratio of a circle's diameter to a circle's circumference.

In this video segment from Cyberchase, the CyberSquad must reclaim the Totally Rad Ring by measuring its radius to create a perfect duplicate.

This task provides a good opportunity to use isosceles triangles and their properties to show an interesting and important result about triangles inscribed in a circle with one side of the triangle a diameter. The fact that these...

In this task, students analyze the characteristics of a right triangle that has two sides labeled with midpoints and show that the triangle is inscribed in a circle with a diameter the length of its hypotenuse. Aligns with G-C.A.2.

[Free Registration/Login Required] This flipchart reviews basic geometric forms in nature and real objects. Students are then given opportunities to find the area of circle and parts of a circle, given the radius and/or diameter of the...

[Free Registration/Login Required] Students identify segments and lines related to circles and the properties of a tangent to a circle.

Includes record sheets and interactive media exploring circles and circumference from general parts of the circle to the relationship of the circle parts.

This site provides a good project for students to use to explore the circumference of a circle.

Learn about the properties of 2-D shapes: circles, triangles, polygons, and quadrilaterals. Includes information, video, and examples about each, with games and quizzes for reinforcement.

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...

Learn all about pi. This lesson targets what is pi, the pi symbol, the pi number, and the pi circle in the concept of what is pi. Check-out the interactive simulations to know more about the lesson and try your hand at solving a few...

Geometry concepts are briefly discussed at this site, including volume of a cylinder, parallelograms, circles, trapezoids, and triangles. Sample problems and applications are included for practice.

Guide a mummy safely through the burial chambers of a pyramid as you solve length and area problems in basic to advanced geometry. There are four game zones that deal with circles and triangles, quadrilaterals, the Pythagorean Theorem,...

Need some ideas for Pi Day on March 14th? You can get some great resources at this location. There are all kinds of links available.

Straightforward lesson that introduces students 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.

[Free Registration/Login Required] Students learn what surface area is on geometric figures, and find volume, lengths, and areas of figures.