CK-12 Foundation
Ck 12: Elem Math: Determine Unknown Angles: Isosceles, Scalene, Right Triangles
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on finding the missing angles in triangles.
CK-12 Foundation
Ck 12: Elem Math: Identifying Rectangles Squares Circles and Triangles
[Free Registration/Login may be required to access all resource tools.] Students watch a video overview and attempt practice problems on identifying rectangles, squares, circles and triangles.
CK-12 Foundation
Ck 12: Triangle Identification as Similar, Congruent, or Neither
[Free Registration/Login may be required to access all resource tools.] Determine whether triangles are similar, congruent, or neither.
Math Is Fun
Math Is Fun: Interactive Triangles
This is an excellent tool for students to explore how changes in the size of a triangle's sides or angles affect its appearance. Different types of triangles and angles are presented.
CK-12 Foundation
Ck 12: Algebra: Applications Using the Pythagorean Theorem
[Free Registration/Login may be required to access all resource tools.] In this lesson students use the Pythagorean Theorem to find lengths and distances. Students watch a video tutorial, explore guided notes and attempt practice problems.
CK-12 Foundation
Ck 12: Algebra: Solving Equations Using the Pythagorean Theorem
[Free Registration/Login may be required to access all resource tools.] Use the Pythagorean Theorem to find a right triangle's missing side lengths.
Math Open Reference
Math Open Reference: Triangle Quiz
Students are assessed on different types of triangles. Definitions of the triangles are included.
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.
Texas Instruments
Texas Instruments: Triangle Proportionality
In this activity, students will study the concept of triangle proportionality. [Requires Adobe Reader.]
Harvard University
University of Harvard: This Is a Stickup!
Students are taught how to make a sundial. The relationship between angles and the sides of a right triangle are explored. Great lesson plan ideas with plenty of background information. The lesson is adapted for grade levels k-6 with...
Purple Math
Purplemath: Basic Triangle Values
This Purplemath lesson explains a simple pictorial way to remember basic reference angle values.
CK-12 Foundation
Ck 12: Pythagorean Triples
[Free Registration/Login Required] Students explore the concept of pythagorean triples by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more about...
CK-12 Foundation
Ck 12: Triangle Classification
[Free Registration/Login Required] Students will move the vertices to different points to create different obtuse triangles. Click learn more to watch a video demonstration and click challenge me to answer a practice question.
CK-12 Foundation
Ck 12: Area and Perimeter of Triangles
[Free Registration/Login Required] Students are given the base and height of a triangle and are to determine the area and perimeter. Click challenge me to answer practice questions and click learn more to watch a video.
Khan Academy
Khan Academy: Find Angles in Isosceles Triangles
Find missing angles in isosceles triangles given just one angle. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
National Council of Teachers of Mathematics
The Math Forum: Analytic Geometry: Polar Coordinates
This site from The Math Forum provides great information on polar coordinates. You can access this information either by clicking on the coordinates link or just scrolling down, it is the first one listed on the page. Includes several...