Curated OER
Playground Mapping
Students review their physical models of the objects on their playground at school. Using the model, they convert it into a map with a scale and key. To end the lesson, they use the map to locate different objects and measure the...
National Council of Teachers of Mathematics
The Math Forum: Triangle Formulas
Investigate the geometric definitions of triangles, focusing upon equilateral, isosceles, right, and scalene with detailed drawings and appropriate formulas for each. This site has links to more information on triangles.
Math Is Fun
Math Is Fun: Constructing a Triangle With 3 Known Sides
Students learn how to construct a triangle with three known sides using a straightedge and a compass. Includes an animated demonstration.
Math Drills
Math Drills: Geometry Worksheets
Download these worksheets to sharpen your geometry skills. Sheets focus on angles, coordinate geometry, triangles, quadrilaterals, transformations, and three-dimensional geometry, and more.
Homeschool Math
Homeschool Math: Triangles
This lesson plan provides students with an opportunity to practice drawing and measuring triangles and angles. It also shows pictures and gives definitions of each type of angle and triangle.
Khan Academy
Khan Academy: Constructing Triangles
Given the lengths of two sides of a triangle, what can we say about the third side? Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
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.
Annenberg Foundation
Annenberg Learner: Constructing Triangles
Use a "linkage strip" to build triangles with different side lengths. When you build a triangle, see if you can deform it into a different triangle while keeping the side lengths the same.
PBS
Pbs Learning Media: Constructing Triangles
This interactive exercise focuses on the appearance and manipulation of triangles.
Government of Alberta
Learn Alberta: Math Interactives: Exploring Square Roots Video
This video illustrates the concepts of square roots, slope, and the Pythagorean Theorem as they are used in designing and constructing skate park rails, ramps, and pipes. An interactive activity is also included where students are able...
Wolfram Research
Wolfram Math World: Equilateral Triangle
MathWorld goes into detail about equilateral triangles at this site. Use this site to find out how to construct an equilateral triangle using a compass and straight edge. Learn about the altitude of such triangles, and the rationality of...
Texas Instruments
Texas Instruments: Sas Triangle Congruence
This activity will help learners visualize the construction of congruent triangles and conceptualize properties through measurement and movement of their construction. Students will need access to the TI-84 Plus Family.
Math Open Reference
Math Open Reference: Congruent Triangles
A complete reference guide to congruent triangles. It provides definitions, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Texas Instruments
Texas Instruments: Investigate Triangles and Congruence
Students can use the TI-84 Plus family with Cabri Jr. to prove triangle congruence with SSA.
Maths Challenge
Maths challenge.net: Perpendicular Construction
This is a "three star" geometry problem where prior math problem skills and proof experience is recommended to solve this "Perpendicular Construction" problem.
National Council of Teachers of Mathematics
The Math Forum: Geoboard Activities
Math Forum provides a set of links to sites that are related to geoboard activities. There are several great links to lessons using geoboards. The links provide insight into how to use them, including how to perform various measurements...
Math Open Reference
Math Open Reference: Constructions
Learn about drawing shapes using only a compass and straight edge or ruler with out measuring any lengths or angles.
Oswego City School District
Regents Exam Prep Center: Reference Angles and Triangles
The mathematics session investigates reference angles and triangles. The tutorial consists of class notes, examples, and practice problems with solutions. The teacher resource includes a worksheet on the construction of skateboarding ramps.
Khan Academy
Khan Academy: Triangle Side Length Rules
Practice solving problems with triangle side length rules.
Math Aids
Math Aids: Geometry
Great resource to practice and strengthen math skills pertaining to Geometry. Math worksheets are printable, may be customized, and include answer keys.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Constructing the Orthocenter
Dr. Math shows how to construct the orthocenter of any triangle using a compass and straight edge.
Wolfram Research
Wolfram Math World: Right Triangle
This site from MathWorld.com offers extensive information on right triangles. The site contains information on numerous characteristics of right triangles, including constructing similar inscribed triangles, altitudes, Pythagorean...
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...