National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Proof the Inscribed Angle Theorem
Dr. Math gives a student a hint on how to prove that an inscribed angle is equal to 1/2 the central angle. You should know what the central angle and inscribed angle are to utilize this site.
Alabama Learning Exchange
Alex: Arc Lengths and Sector Areas
Students will work in cooperative groups to discover the relationships between arc length, central angle measure, and circumference. They will also discover the relationship between circle area, central angle measures, and sector area....
Texas Instruments
Texas Instruments: Smile Mathematics App
This App contains five games that reinforce skills from the number and operations, geometry, and measurement standards. These games help students build skills in ordering numbers, choosing equivalent fractions, estimating and drawing...
Mangahigh
Mangahigh: Shape: Quadrilaterals Inscribed in Circles
Determine the missing angle measures of quadrilaterals inscribed in circles.
Khan Academy
Khan Academy: Constructing Triangles
Practice constructing triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Oswego City School District
Regents Exam Prep Center: Parallel Lines
Material to supplement classroom instruction on parallel lines: a lesson on angles with parallel lines, a practice quiz, and a link to an investigation on angles with parallel and non-parallel lines.
PBS
Pbs: Black Kingdoms of the Nile
A geometry lesson that examines the history and structure of ancient pyramids and engages students in constructing pyramid models. A comprehensive lesson that considers students with diverse learning styles. Math concepts introduced...
Math Planet
Math Planet: Geometry: More About Triangles
Explores triangles and related vocabulary through examples and a video lesson.
Purple Math
Purplemath: Conventions
A "convention" is "just the way a thing is done!". This reference material lists some common conventions (notational assumptions) for geometry and trigonometry.
Better Lesson
Better Lesson: Differences With Shapes
Differences between shapes are determined through measurement skills.
University of Saskatchewan (Canada)
Finding Arc Length and Central Angle Exercises
This site provides two geometry problems involving circles. One problem has the reader find the arc length given the angle and radius, the other problem has the reader find the measure of the angle given the arc length and radius....
Other
Ohio Department of Education: Eighth Grade Achievement Test (Practice Test)[pdf]
Half-length practice test for the eighth grade OAT (Ohio Achievement Test). The test includes 15 multiple-choice and 4 open-response questions dealing with topics such as geometry (comparing volumes, angle measures), data analysis...
Math Is Fun
Math Is Fun: Using a Protractor
Students learn how to construct and measure angles using a protractor and ruler. The resource consists of a video demonstration and exploration activity.
Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: Similarity
This site contains a lesson plan for high school age learners. The objective is to discover the factor of proportionality in similar polygons and to relate this factor to the perimeters and areas of similar polygons.
Khan Academy
Khan Academy: Determine Similar Triangles: Aa
Given two triangles with some of their angle measures, determine whether the triangles are similar or not. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
CK-12 Foundation
Ck 12: Isosceles Triangles
[Free Registration/Login Required] Students are given an Isosceles triangle and are asked to move the point on the line segment to explore how the angle measure changes. Click learn more to watch a video demonstration and click challenge...
Khan Academy
Khan Academy: Sequences of Transformations
Given a description of a sequence of transformations, determine whether it preserves segment length or angle measure. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
Maths Challenge
Maths challenge.net: Right Triangle Equal Parts
A geometry proof problem involving a right triangle and finding angles of equal measure.
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.
Khan Academy
Khan Academy: Arc Length
Relate the length of an arc to the circumference of a whole circle and the central angle subtended by the arc. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
National Council of Teachers of Mathematics
Nctm: Figure This: Math Challenges for Families
Students, teachers, and parents alike will enjoy this challenging math site. It contains a clever brain teaser section plus creative problems related to algebra, geometry, measurement, numbers, statistics, and probability. A Spanish...
National Council of Teachers of Mathematics
Nctm: Figure This: Windshield Wipers
Test your mathematical aptitude with challenge exploring the concepts of measurement and geometry. Find the area of the windshield wipers to figure out who sees better in the rain, car drivers or truck drivers. An activity from the NCTM...
Integrated Publishing
Plane Figures
This site describes lines and angles "as found in various plane (flat) geometric figures.".
Illustrative Mathematics
Illustrative Mathematics: G Gpe, F Tf Coordinates of Points on a Circle
For this task, students 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 purpose...