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,...
Learning Wave Communications
Learning Wave: Geometry, Section 2
Geometry concepts are briefly discussed at this site, including volume of a cylinder, parallelograms, circles, trapezoids, and triangles. Sample problems and applications are included for practice.
Wolfram Research
Wolfram Math World: Circle
This site from Mathworld provides a wealth of information about circles is presented. The information ranges from the basics--radius, circumference, etc.--to advanced concepts--equations in polar and pedal coordinates, etc.
Homeschool Math
Homeschool Math: Circles
Lesson presents definitions of terms associated with circles and helps students learn to use a compass to draw circles and simple circle designs.
Texas Instruments
Texas Instruments: Relationship of Angles to the Circle
In this activity, students recognize the relationship of angles to circles. They study the Inscribed Angle Theorem and its corollaries.
Illustrative Mathematics
Illustrative Mathematics: G C Two Wheels and a Belt
A certain machine is to contain two wheels, one of radius 3 centimeters and one of radius 5 centimeters, whose centers are attached to points 14 centimeters apart. The manufacturer of this machine needs to produce a belt that will fit...
Rice University
Rice University: Cynthia Lanius: Circles Around Pythagoras
This site from the Rice University includes a fill-in-the-blank lesson on the definition of circles, as Pythagoras described.
Other
Sprk: Orb Basic Lesson 2 [Pdf]
Young scholars will use Sphero to explore the computer science concepts of variables and conditionals (ifstatements). They will use OrbBasic, which is a text-based programming language for the Sphero. They will write a simple program...
Texas Instruments
Texas Instruments: Numb3 Rs: Meltdown
Based off of the hit television show NUMB3RS, this lesson has students explore the relationship between a circle's area and it's radius. This is framed in the context of a scene in where a pile of ice is melting into an increasingly...
Analyze Math
Analyze Math: Polygons Problems
Here are four problems about the area of a regular polygon. Start by finding the area of a hexagon inscribed in a circle of radius 10, and end by proving that as the number of sides of the polygon increases, the area of the polygon...
PBS
Pbs Learning Media: Tricking Hacker
In this video segment from Cyberchase, the CyberSquad must reclaim the Totally Rad Ring by measuring its radius to create a perfect duplicate.
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.
Math Open Reference
Math Open Reference: Diameter
A complete reference guide to diameters. It provides definitions, examples, and interactive activities that enhance further explanation. Includes links to related topics.
Texas Instruments
Texas Instruments: Segments Formed by Intersecting Chords, Secants, and Tangents
This activity is designed to help students discover several important theorems concerning lengths of segments formed by intersecting chords, secants, and tangents.
Texas Instruments
Texas Instruments: Chords, Secants, and Tangents
Students construct chords, secants, and tangents. From those constructions, they develop a deeper understanding of the terms, as well as explore certain properties of the constructions.
Wolfram Research
Wolfram Math World: Apothem
MathWorld offers a definition of the apothem of a circle as well as an illustration is provided on this page. An equation is also provided to calculate the apothem of a circle given the radius and the sagitta.
Calculator Soup
Calculator Soup: Conical Frustum Calculator
This online calculator will calculate the various properties of a conical frustum given the 2 radii and any 1 other known variable.
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Geometry in the Plane
Twenty-four problems presented on a variety of Plane Geometry topics. They are given with each step to the solution cleverly revealed one at a time. You can work each step of the problem then click the "View Solution" button to check...
Khan Academy
Khan Academy: Radians and Arc Length
Solve problems related to radians and arc length like finding an arc length given the central angle and radius. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Cuemath
Cuemath: What Is Pi?
Learn all about pi. This lesson targets what is pi, the pi symbol, the pi number, and the pi circle in the concept of what is pi. Check-out the interactive simulations to know more about the lesson and try your hand at solving a few...
Cuemath
Cuemath: Arc Length
Learn all about arc length. This lesson targets what is arc length and the different formulas used to calculate it. Check-out the interactive simulations to know more about the lesson and try your hand at solving a few interesting...
National Council of Teachers of Mathematics
The Math Forum: Multicultural Math Fair: Srinivasa's Spheres
Straightforward lesson that introduces learners 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 and Spanish.
Math Open Reference
Math Open Reference: Sector
Learn about sectors with this handy reference guide. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.
Quia
Quia: Geometric Terms Concentration
Do you need practice remembering or learning different geometry vocabulary words and definitions? This concentration game is the web site for you! There is a link to a list of terms with definitions you can click if you want to see if...