University of St. Andrews (UK)
University of St. Andrews: James Gregory
This site, which is provided for by the University of St. Andrews, contains information on the mathematician Gregory and his accomplishments.
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.
CK-12 Foundation
Ck 12: Geometry: Segments From Secants
[Free Registration/Login may be required to access all resource tools.] Apply the Two Secants Segments Theorem.
CK-12 Foundation
Ck 12: Elem Math: Identifying Semi Circles and Quarter Circles
[Free Registration/Login may be required to access all resource tools.] The video defines a semi-circle and a quarter-circle and answers a question determining which object is a semi-circle. The video is followed by a series of practice...
CK-12 Foundation
Ck 12: Geometry: Arcs in Circles
[Free Registration/Login may be required to access all resource tools.] In this lesson students apply the properties of arcs and central angles. Students examine guided notes, review guided practice, watch instructional videos and...
CK-12 Foundation
Ck 12: Elem Math: Counting Semi Circles and Quarter Circles in Composite Figures
[Free Registration/Login may be required to access all resource tools.] The video defines composite figures, semi-circles, and quarter circles, then uses those definitions to determine how many semi-circles and quarter circles are in the...
CK-12 Foundation
Ck 12: Geometry: Properties of a Circle Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide reviews the terminology for circles (tangent, arcs, central angles) and the equation for a circle.
Mathigon
Mathigon: Geometry: Circle and Pi: Introduction
This lesson focuses on the characteristics of a circle including similarity, radius, circumference, and Pi. It provides formulas to determine the area of a circle, calculating Pi, and learning exercises throughout.
CK-12 Foundation
Ck 12: Geometry: Radius or Diameter of a Circle Given Area
[Free Registration/Login may be required to access all resource tools.] Find the radius or diameter of a circle given its area.
CK-12 Foundation
Ck 12: Geometry: Radius or Diameter of a Circle Given Area
[Free Registration/Login may be required to access all resource tools.] Find the radius or diameter of a circle given the area of the circle
CK-12 Foundation
Ck 12: Geometry: Angles Outside a Circle
[Free Registration/Login may be required to access all resource tools.] Solve problems containing angles outside a circle.
CK-12 Foundation
Ck 12: Geometry: Arc Length
[Free Registration/Login may be required to access all resource tools.] In this lesson students find the length of an arc. Students examine guided notes, review guided practice, watch instructional videos and attempt practice problems.
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...
CK-12 Foundation
Ck 12: Geometry: Angles on and Inside a Circle Intermediate
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to find angles on and inside a circle created by chords and tangent lines.
CK-12 Foundation
Ck 12: Geometry: Angles on and Inside a Circle
[Free Registration/Login may be required to access all resource tools.] Solve problems containing angles on or inside a circle.
Common Core Sheets
Common Core Sheets: Geometry 7.g.4 Worksheets: Area and Circumference Circle
Worksheets provide practice with finding the area or circumference of a circle and answer keys are provided. You can even create your own instructional activity or flashcards.
Alabama Learning Exchange
Alex: "Introducing Pi!"
The overriding purpose of the lesson is to actively engage students in learning activities that promote opportunities for students to discover the 'meaning' of pi. Activities will include research, hands-on, software applications,...
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.
Alabama Learning Exchange
Alex: Geometric Quilts
Young scholars will use a square to investigate other polygonal shapes that can be formed. Students will work with these polygons to make designs that will later constitute cooperatively designed quilts. The quilts will be made by...
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.
Alabama Learning Exchange
Alex: Discovering Pi
This lesson allows students to discover the number Pi. By measuring real life objects, students will get to see where the number Pi comes from as well as how the circumference formula is derived.This lesson plan was created as a result...
Alabama Learning Exchange
Alex: Area and Perimeter of Various Polygons
In this lesson plan students will be engaged in an interactive online practice session using area and perimeter. Students will have to use critical thinking skills in order to unlock gates and learn more about the cups in the challenge.
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: Angles in Circles Word Problems
Practice word problems that involve thinking about angles as part of a circle.