Khan Academy
Khan Academy: Points Inside/outside/on a Circle
Given the center and radius of a circle, determine if a point is inside of the circle, on the circle, or outside of the circle.
CK-12 Foundation
Ck 12: Elem Math: Classify Objects as Rectangles, Squares, Circles, or Triangles
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on classifying rectangles, squares, circles and triangles.
CK-12 Foundation
Ck 12: Elem Math: Identifying Rectangles Squares Circles and Triangles
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview and attempt practice problems on identifying rectangles, squares, circles and triangles.
CK-12 Foundation
Ck 12: Circles in the Coordinate Plane
[Free Registration/Login Required] Students will move points on a circle to explore standard equations when given the radius and center. Click challenge me to answer practice problems and click learn more to watch a video.
CK-12 Foundation
Ck 12: Circles in the Coordinate Plane: Watering the Field
[Free Registration/Login Required] Students can move points in a circle to determine the standard equation from the raidus and center. Click challenge me to answer practice questions and click learn more to watch a video.
Common Core Sheets
Common Core Sheets: Geometry 8.g.3 Worksheets: Coordinate Plane
Worksheets provide practice with finding the area or circumference of a circle and answer keys are provided. You can even create your own worksheet or flashcards.
Illustrative Mathematics
Illustrative Mathematics: G Co Seven Circles Ii
In this task, seven pennies are placed in a circle so that they are all touching one in the center and their neighbors. Students are asked to find as many rigid motions of the plane as they can which are symmetries of this configuration...
Oswego City School District
Regents Exam Prep Center: Area of Polygons and Circles
How would you find the area of a polygon or circle? Explore this concept with engaging activities at this test prep site. Here you will find detailed problem solving strategies with accompanying visuals, a reference table with formulas,...
Walter Fendt
Walter Fendt: Apps on Mathematics
Apps for Arithmetic, Plane Geometry, and other Geometry concepts are provided.
CK-12 Foundation
Ck 12: Interactive Geometry: 10.1 Conic Sections
The conic sections are the cross-sections of a double-napped cone. Depending on the angle of the plane with respect to the cone, a conic section may be a circle, an ellipse, a parabola, or a hyperbola.
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.
Mangahigh
Mangahigh: Pyramid Panic: Basic Shapes to Advanced Geometry
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,...
CK-12 Foundation
Ck 12: Geometry: Inscribed Angles in Circles
[Free Registration/Login may be required to access all resource tools.] Apply inscribed angle theorems.
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.
Illustrative Mathematics
Illustrative Mathematics: G Gpe, F Tf Coordinates of Points on a Circle
For this task, young scholars are shown a unit circle in a plane and an angle measured from the x-axis. They must determine the coordinates of the line segment for the angle and answer a question about the sum of the coordinates. The...
ClassFlow
Class Flow: Circles and Angles
[Free Registration/Login Required] In this flipchart students practice identifying parts of a circle, measure angles, and practice solving area and circumference problems.
E-learning for Kids
E Learning for Kids: Math: Group of Pyramids: 2 D Shapes
Abeni works at the pyramids. Visit her and find out more about circles and triangles.
National Council of Teachers of Mathematics
The Math Forum: Analytic Geometry: Polar Coordinates
This site from The Math Forum provides great information on polar coordinates. You can access this information either by clicking on the coordinates link or just scrolling down, it is the first one listed on the page. Includes several...
University of Texas at Austin
Mathematics Teks Toolkit: Exploring C/d= Pie
A collection of circular objects will be used to explore circumference and diameter of circles.
E-learning for Kids
E Learning for Kids: Math: Market Place: 2 D Shapes and Patterns
On this interactive site, students learn to identify squares, circles, and triangles.
Cuemath
Cuemath: Tangent
Learn about the tangent definition in geometry, tangent geometry, tangent to a circle, tangent line equation. Check-out the solved examples for better understanding and try your hand at the tangent line calculator or solving a few...
Curated OER
Circle Picture
This site provides definitions for different parts of a circle, pictures to more clearly represent formulas involving circles. Some of the formulas discussed include: area of a circle, area of a sector of a cirles, circumference, length...
E-learning for Kids
E Learning for Kids: Math: Music: 2 D Shapes
Kyan is an African villager. Can you help him name and define different parts of shapes?
PBS
Pbs Mathline: Bubble Mania Lesson Plan [Pdf]
Determine the area, diameter, and circumerfence of a bubble residue by creating a soap solution and blowing bubbles.