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.
Wolfram Research
Wolfram Math World: Pi
This site from Mathworld.com provides a detailed overview of pi. Content includes a diagram, an analysis of its value, how and when pi crops up in mathematics, historical references to pi, and more.
University of North Carolina
A Dictionary of Units of Measurement
This site contains an extensive list of various units of measurement known internationally and across several disciplines. Unit symbols are also included.
Other
Ic Teachers: Shapes, Circles (Basic)
This basic website will give you lots of information about circles. There are also some questions to test your circle knowledge.
CK-12 Foundation
Ck 12: Geometry: Area of a Circle
[Free Registration/Login may be required to access all resource tools.] In this lesson students calculate the area of circles and the area of sectors of circles by using given information and formulas. Students examine guided notes,...
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.
CK-12 Foundation
Ck 12: Geometry: Inscribed Angles in Circles
[Free Registration/Login may be required to access all resource tools.] This concept teaches students properties of inscribed angles and how to apply them.
CK-12 Foundation
Ck 12: Geometry: Inscribed Quadrilaterals in Circles
[Free Registration/Login may be required to access all resource tools.] This concept teaches students properties of inscribed quadrilaterals in circles.
CK-12 Foundation
Ck 12: Geometry: Parts of Circles
[Free Registration/Login may be required to access all resource tools.] This concept teaches students the vocabulary for the parts of circles, including lines passing through circles.
CK-12 Foundation
Ck 12: Pi
[Free Registration/Login Required] Students will determine Pi by exploring the points on a circle. Click challenge me to answer practice questions and click learn more to watch a video.
Math Open Reference
Math Open Reference: Circles
A complete reference guide to circles including parts, angles, and arcs. It provides definitions and interactive activities that enhance further explanation.
BBC
Bbc: Bitesize: Maths: 2 D Shapes
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.
Rice University
Rice University: Cynthia Lanius: Mathematics of Cartography
Can there be a connection between map making and math? Explore the mathematics of cartography in this resource that integrates web-based instruction, mathematical problem solving, geometry, history, and art. Interesting information and...
CK-12 Foundation
Ck 12: Geometry: Arc Length
[Free Registration/Login may be required to access all resource tools.] This concept teaches students to find the length of an arc. Students examine guided notes, review guided practice, watch instructional videos and attempt practice...
Math Open Reference
Math Open Reference: Parts of a Circle
Learn about parts of a circle with this pictorial index. Click on the diagrams for more information. Includes links to related topics.
Math Open Reference
Math Open Reference: Radius of a Circle
Learn about the radius of a circle with this useful reference guide. Provides a detailed definition, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Cuemath
Cuemath: Radius
This reference tool explores the radius of a circle. Provides definitions, solved examples, and practice questions with answers.
Math Open Reference
Math Open Reference: Area Enclosed by a Circle
A complete reference guide to the area enclosed by a circle. It provides definitions, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Quia
Ixl Learning: Area of Circles
Brush up on your math skills relating to the area of circles then try some practice problems to test your understanding.
Quia
Ixl Learning: Pi
Brush up on your math skills relating to pi then try some practice problems to test your understanding.
Math Open Reference
Math Open Reference: Pi
Learn about Pi with this helpful reference tool. Provides a detailed definition and examples that enhance further explanation. Includes links to related topics.
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.
National Council of Teachers of Mathematics
The Math Forum: Multicultural Math Fair: Srinivasa's Spheres
Straightforward instructional activity 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...
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