SEDL
The Timss Mathematics Segment: Geometry
This site explores the area of congruent triangles and how it is a difficult area to understand.
Curated OER
Nova Scotia Dept. Of Education: Mathematics 8: Geometry Diagrams
A collection of diagrams that complement Mathematics 8, a Grade 8 Math text, have been posted here. The diagrams were created using The Geometer's Sketchpad,
Texas Instruments
Texas Instruments: Cabri Jr. Getting Started With Triangles
This activity was developed as an introduction to the Cabri Jr. application on the TI-84 calculator. It investigates some basic properties of triangles. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: Walking the Fence Line, Then the Hypotenuse
In this activity, students use the Geoboard to determine the length of the hypotenuse of a right triangles. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: The Simson Line
Students study the Simson line and analyze the relationship it shares with its triangle. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: Math Today Dangerous Births
In this activity, using the USA TODAY Snapshot "Dangerous births" students will explore the geometric relationships of triangles using perpendicular bisectors of the sides, bisectors of the angles and medians of the triangle. They will...
Texas Instruments
Texas Instruments: Try Angle?
In this activity, students investigate properties of triangles by randomly generating possible side lengths for triangles. They learn to determine if three line segments can form a triangle. They also learn to classify triangles as...
Texas Instruments
Texas Instruments: Investigating Special Trangles
This activity will help students visualize the construction of these special triangles and find the ratios of the sides. It will help students later when they being trigonometry. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: Classifying Triangles by the Length of the Sides Using Cabri
This activity uses Cabri Jr. to classify triangles according to the length of their sides. [Requires Adobe Reader.]
Math Planet
Math Planet: Algebra 2: Trigonometric Functions
Get information about trigonometric functions by viewing examples and a video lesson. [2:08]
Math Planet
Math Planet: Algebra 2: Sines
Defines and examines the law of sines through examples and a video lesson. [2:02]
Math Planet
Math Planet: Geometry: Congruent Triangles
Features a definition and a video lesson on congruent triangles with examples. [1:11]
Scholastic
Scholastic: Study Jams! Math: Geometry: Classify Triangles
After completing the lesson on classifying triangles, you can sing along with karaoke and test your knowledge.
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Triangulos
In Spanish. This interactive activity shows how to compute the area of a triangle and the concept of altitude, median and angle bisector. [Requires Java.]
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Teselacion Del Plano
In Spanish. Gain your knowledge of tessellation with this interactive activity. Topics include identifying regular and semi-regular tessellations and figures that will tessellate. [Requires Java.]
Writing Fix
Writing Fix: Useful Shapes: Analytical Writing in Primary Math Classrooms
In this lesson, the book entitled The Greedy Triangle, written by Marilyn Burns, is shared. After sharing this read-aloud book, students will illustrate pictures that incorporate the triangle. Then will write three reasons why a triangle...
Math Planet
Math Planet: Geometry: More About Triangles
Explores triangles and related vocabulary through examples and a video lesson.
Math Planet
Math Planet: Geometry: Triangles: Inequalities
Gain an understanding of how to list the sides of a triangle in order from shortest to longest by viewing examples and a video lesson. [1:01]
McGraw Hill
Glencoe Mathematics: Online Study Tools: Triangles and Angles
This site gives a short interactive quiz which allows students to self-assess their understanding of the concept of triangles and angles.
McGraw Hill
Glencoe Mathematics: Online Study Tools: Self Check Quiz on Triangles
Students show comprehension of Geometry skills. The online quiz assesses scholars on relationships in triangles.
Sophia Learning
Sophia: Triangle Exterior Angles Practice: Lesson 5
This lesson provides practice problems that apply the triangle exterior angles theorem. It is 5 of 6 in the series titled "Triangle Exterior Angles Practice."
University of Cambridge
University of Cambridge: Maths and Sports: Stadium Sightline
How would you design the seating for an Olympic stadium to give spectators the best view of events? This geometry and modelling activity is designed to be accessible to both GCSE and A-level maths students (Key Stage 4 and Key Stage 5),...
Illustrative Mathematics
Illustrative Mathematics: 6.g Same Base and Height, Variation 1
Make the following triangles on a geoboard. Remember that the pegs are equally spaced in a square grid. Compare the areas of the triangles. Aligns with 6.G.A.1.
Illustrative Mathematics
Illustrative Mathematics: 6.g Base and Height
The purpose of this task is to help students understand what is meant by a base and its corresponding height in a triangle and to be able to correctly identify all three base-height pairs. Aligns with 6.G.A.1.