Khan Academy
Khan Academy: Challenge Problems: Inscribed Shapes
Solve three challenging problems that apply properties of inscribed shapes to find an arc length or a missing angle.
Cuemath
Cuemath: Central Angle
Learn all about the basic properties of central angles. This lesson targets what is a central angle, central angle formula, central angle calculator, theorem of central angle, how to find central angles, and how to apply them while...
TED Talks
Ted: Ted Ed: Why Are Manhole Covers Round?
Why are most manhole covers round? Sure it makes them easy to roll, and slide into place in any alignment. But there's another, more compelling reason, involving a peculiar geometric property of circles and other shapes. Marc Chamberland...
University of Cambridge
University of Cambridge: Maths and Sports: Sports Equipment
Sports such as hockey, football, basketball and tennis use balls of different sizes. Can you arrange a selection of different balls in a line each touching the next to make the shortest line? This activity offers opportunities for...
Curated OER
Research Pages: Circle Inversion Fractals
This site introduces the iteration of circle inversions and describes the associated properties.
Curated OER
Research Pages: Circle Inversion Fractals
This site introduces the iteration of circle inversions and describes the associated properties.
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.
Analyze Math
Analyze Math: Regular Polygons
The interactive tutorial examines the properties and formulas of regular polygons, inscribed circles, and circumscribed circles.
Other
Antonio Gutierrez: Geometry From the Land of the Incas
Discovering the properties of constructions, seeing proofs in action, and viewing problems come to life here with this wonderful use of technology in the classroom. Single steps are explained and illustrated one at a time so that the...
CK-12 Foundation
Ck 12: Interactive Geometry: 9.3 Spheres
Learn how the components and properties of a sphere are analogous to those of a circle.
Animal Fact Guide
Animal Fact Guide: Narwhal Whales
Read facts about the narwhal including information on its physical characteristics, habitat (with a distribution map), diet, breeding patterns, unique traits and behavior, conservation status, and tips on what you can do to help.
Illustrative Mathematics
Illustrative Mathematics: G Co Origami Equilateral Triangle
The purpose of this task is to explore reflections in the context of paper folding. Each fold is associated with a line of reflection and understanding each step in the construction requires careful analysis of angles and of the...
Texas Instruments
Texas Instruments: Real Numbers
Students learn to identify real numbers as rational numbers and irrational numbers. They review rational numbers as repeating decimals, and irrational numbers as non-repeating decimals. They also review commutative, associative,...
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.
Paul Dawkins
Paul's Online Notes: Algebra Cheat Sheet [Pdf]
An algebra "cheat sheet" to use as a reference when completing algebra homework. Lists basic facts, properties, operations, formulas, and functions, as well as common errors.
Calculator Soup
Calculator Soup: Cone Calculator
This online calculator will calculate the various properties of a right circular cone given any 2 known variables.
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.
ClassFlow
Class Flow: Loci
[Free Registration/Login Required] Students learn how to apply geometric properties and relationships to describe, compare, and draw two dimensional shapes.
Khan Academy
Khan Academy: Challenge Problems: Radius & Tangent
Solve two challenging problems that apply properties of tangents to find the radius of a circle with a tangent.
Khan Academy
Khan Academy: Determining Tangent Lines: Lengths
Solve two problems that apply properties of tangents to determine if a line is tangent to a circle.
Khan Academy
Khan Academy: Determining Tangent Lines: Angles
Solve two problems that apply properties of tangents to determine if a line is tangent to a circle.
Khan Academy
Khan Academy: Name Shapes 3
Practice identifying circles, triangles, squares, rectangles, rhombuses, trapezoids, and hexagons. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Khan Academy
Khan Academy: Challenge Problems: Circumscribing Shapes
Solve two challenging problems that apply properties of tangents to find the perimeter of a circumscribing shape.
Quia
Quia: Geometric Terms Matching
Do you need practice remembering or learning different geometry vocabulary words and definitions? This matching 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 you are...