Hi, what do you want to do?
Khan Academy
Khan Academy: Radius and Diameter
Practice problems finding radius and diameter of a circle.
National Council of Teachers of Mathematics
Nctm: Illuminations: Circle Area
Explore what the relationship the radius has to the area of a circle. Click the instructions to learn how to use this interactive resource and select"Exploration" for more ideas.
Texas Instruments
Texas Instruments: Match the Graph (Circles)
Students will learn about the equation for a circle by using a Study Cards stack. Later, students will attempt to match the graph of a circle from a digital picture, using the form learned previously, and approximating the center and...
Texas Instruments
Texas Instruments: Circles in the Plane
In this activity, students can use the Cabri Jr. application to explore circles in a plane. They will investigate the relationship between the equation of a circle, the length of its radius, and the coordinates of its center. [Requires...
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.
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: Circles in the Coordinate Plane
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to graph circles and find the standard equations of circles. Students examine guided notes, review guided practice, watch...
Physics Classroom
The Physics Classroom: Circular & Satellite Motion: Uniform Circular Motion
Manipulate variables while exploring principles and relationships related to moving in a circle at a constant speed. Students change the radius of the circle, the speed of the object, and the mass of the object and investigate the effect...
Illustrative Mathematics
Illustrative Mathematics: G Gpe Explaining the Equation for a Circle
This problem examines equations defining different circles in the x-y plane. Students must use the Pythagorean Theorem to find equations whose solutions are points on the circle and explain why they work. Includes a GeoGebra worksheet...
Texas Instruments
Texas Instruments: Math Today Coming Clean About Showering Time
In this activity using the USA TODAY Snapshot, "Coming clean about showering time," students will find the measures of central angles and arcs of a circle. They will use circumference, radius, concentric circles and degrees in a circle...
McGraw Hill
Glencoe Mathematics: Online Study Tool: Self Check Quiz on Circles
The online assessment exhibits knowledge of advanced mathematical concepts in Trigonometry. The questions evaluate students on the topic of circles.
Math Is Fun
Math Is Fun: Definition of Circumference
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.
Cuemath
Cuemath: Cone
Learn all about the basic properties of a cone. This lesson targets the formula, volume, parts, and shapes of a cone and has interesting solved examples and practice questions.
Mathigon
Mathigon: Geometry: Circle and Pi: Degrees and Radians
Rather than dividing a circle into some number of segments (like 360 degrees), mathematicians often prefer to measure angles using the circumference of a unit circle - a circle with radius 1. This way of measuring angles is called...
Illustrative Mathematics
Illustrative Mathematics: F Tf.1 What Exactly Is a Radian?
For this task, students use a piece of string or another tool to measure the radius of the circle and then mark off the corresponding arc length on the unit circle as many times as they need to for 0, 1, 2, 3, 4, 5, and 6 radians. They...
Texas Education Agency
Texas Gateway: Circular Motion & Gravitation: Rotation Angle & Angular Velocity
By the end of this section, you will be able to define arc length, rotation angle, radius of curvature, and angular velocity; and to calculate the angular velocity of a car wheel spin.
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.
Mocomi & Anibrain Digital Technologies
Mocomi: What Is Circle?
Discusses the radius, diameter, circumference, and area of a circle.
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.
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.
Texas A&M University
Wtamu Virtual Math Lab: College Algebra: Circles
Use this tutorial to learn about the standard-form equation for a circle. Several step-by-step solutions and examples help you understand the part of the circle and how they relate to the equation.
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.
ClassFlow
Class Flow: Completing the Square Circles
[Free Registration/Login Required] This flipchart is a simple and basic flip chart showing how to find the center and radius of a circle that is in standard form as well as completing the square for equations of circles that are not in...
Oswego City School District
Regents Exam Prep Center: Area of Polygons and Circles
A lesson focusing on the area of polygons and the circumference of circles. Engaging, interactive practice worksheet, lesson plan, and related classroom activity complete this lesson.