PBS
Pbs Learning Media: Finding the Circle's Center
In this video segment [3:10] from Cyberchase, the CyberSquad must find the exact center of a circle in order to save Motherboard.
Discovery Education
Discovery Education: Web Math: Find Out Things About Circles
This WebMath site will assist with finding the radius, diameter, circumference, and area of a circle.
CK-12 Foundation
Ck 12: Examining Circles: Area of a Circle
[Free Registration/Login Required] Students use the radius and diameter to determine the area of a circle. Click challenge me to answer practice questions and click learn more to watch a video.
CK-12 Foundation
Ck 12: Area of a Circle: Hula Hoop Radius
[Free Registration/Login Required] Students use the radius and diameter to determine the area of a circle. Click challenge me to answer practice questions and click learn more to watch a video.
CK-12 Foundation
Ck 12: Area of a Circle: Campsite
[Free Registration/Login Required] Students are given the radius and diameter to solve for the area of a circle. Click challenge me for practice problems and click learn more to watch a video.
Math2
Math2: Circles
This site has many useful formulas and examples relating to circles, including related definitions, circumference of a circle, area of a circle, length of a circular arc, area of a circular sector, equation of a circle in cartesian...
Mr. Martini's Classroom
Mr. Martini's Classroom: Circles Geometry Review
This resource provides two levels of multiple choice questions to review the parts of a circle as well as area and perimeter.
Wolfram Research
Wolfram Math World: Diameter
This site shows what a diameter is, how to find one on a circle or a sphere, and provides the formula to find diameter of a circle or "the great circle of a sphere.
Varsity Tutors
Varsity Tutors: Hotmath: Algebra Review: Diameter
Find a quick, concise explanation of what the diameter of a circle is. An example is given and clearly explained.
OER Commons
Oer Commons: Measuring Circles
Seventh graders will measure the circumference and diameter of round things in the classroom and discover the ratio pi. They will see that the ratio of a circle's circumference to its diameter can be used to solve for the circumference...
Cuemath
Cuemath: Diameter
Understand the concept of diameter by learning the definition and symbols. Check-out the solved examples for better understanding and try your hand at solving a few interactive questions at the end of the page.
Khan Academy
Khan Academy: Radius and Diameter
Practice problems finding radius and diameter of a circle.
Texas Instruments
Texas Instruments: Circles All Around
This activity provides students an opportunity to explore the relationship between the diameter of a circle and its circumference. [Requires Adobe Reader.]
Alabama Learning Exchange
Alex: Talking in Circles
The students will identify parts of the circle including center, radius, diameter, chord, and arc. This lesson plan was created by exemplary Alabama Math Teachers through the AMSTI project.
E-learning for Kids
E Learning for Kids: Math: World of Fish: Geometry
Students will play an interactive game to identify the circumference, radius, center, and diameter of circles.
Houghton Mifflin Harcourt
Holt, Rinehart and Winston: Homework Help Independent Practice: Circles
Get independent practice working with finding the circumference, area and radius of circles. Each incorrect response gets a text box explanation and another try. Correct responses are confirmed.
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.
ClassFlow
Class Flow: Area of a Circle
[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...
TeachEngineering
Teach Engineering: Let's Take a Slice of Pi
Working as a team, students discover that the value of pi (3.1415926) is a constant and applies to all different sized circles. The team builds a basic robot and programs it to travel in a circular motion. A marker attached to the robot...
CK-12 Foundation
Ck 12: Geometry: Circle Circumference
[Free Registration/Login may be required to access all resource tools.] In this lesson students find the circumference of a circle given the radius or the diameter. Students examine guided notes, review guided practice, watch...
CK-12 Foundation
Ck 12: Geometry: Circle Circumference
[Free Registration/Login may be required to access all resource tools.] In this lesson students find the circumference of a circle given its diameter or radius. Students examine guided notes, review guided practice, watch instructional...
CK-12 Foundation
Ck 12: Geometry: Parts of Circles
[Free Registration/Login may be required to access all resource tools.] Name the parts of a circle.
Texas Instruments
Texas Instruments: Approximation of Pi
Students will measure the circumference and diameter of a variety of different circles. They will graph the class' values of (d,c) on the coordinate plane and use linear regression to approximate pi.
Calculator Soup
Calculator Soup: Circle Calculator
Use this circle calculator to find the area, circumference, radius, or diameter of a circle. Given any one variable A, C, r or d of a circle you can calculate the other three unknowns.