Concord Consortium
Three Rubber Bands
Stretch your mind about triangles. Given a triangle, scholars consider a smaller triangle formed when they stretch three rubber bands from each vertex to the opposite side. They determine the ratios of the areas and perimeters of the...
Shodor Education Foundation
Triangle Area
While the lesson plan focuses on right triangles, this activity offers a great way to practice the area of all triangles through an interactive webpage. The activity begins with the class taking a square paper and cutting in in half; can...
Texas Instruments
Identifying a Triangle by its Sides and Angles
Identify triangles by their angle measures and side lengths by looking at and measuring angle measures and side lengths. Use Cabri Jr. to construct various triangles, then manipulate the construction to create the 6 types of triangles,...
Illustrative Mathematics
Lines of Symmetry for Triangles
What can symmetry tell us about triangles? After looking at four examples, learners will come to realize that lines of symmetry are different for equilateral, isosceles, and scalene triangles. Use this guided practice activity as an...
Concord Consortium
Isosceles Triangle Spaces
How many different types of triangles can your class name? A discovery lesson guides learners through an exploration of the different triangle types and the relationships between their angles and sides. Using coordinate geometry,...
Curated OER
Exploring the Circumcenter of a Triangle
Students construct the circumcenter of a triangle. In this constructing the circumcenter of a triangle lesson, students construct a triangle using Cabri Jr. Students draw perpendicular bisectors of the sides of the triangle. Students...
Curated OER
Triangle Inequality Theorem
High schoolers investigate the relationship between angle measures and sides of a triangle and the relationships among the three sides of a triangle. The use of technology (Cabri, Jr.) allows learners to make and test conjectures as they...
Mathematics Vision Project
Module 5: Modeling with Geometry
Solids come in many shapes and sizes. Using geometry, scholars create two-dimensional cross-sections of various three-dimensional objects. They develop the lesson further by finding the volume of solids. The module then shifts...
Curated OER
Triangle in the Matrix
Young mathematicians represent a triangle with a matrix and use the determinant to find the area of three given triangles. Learners also verify the formula for area of a triangle.
Curated OER
Triangle Sum Theorem
Teach your class how to solve problems using the triangle sum theorem. In this geometry lesson, students identify the missing angles in a triangle using the sum theorem. They graph triangles on the TI and moves the sides around to create...
Curated OER
Investigating Segments in a Right Triangle
High schoolers explore the concept of right triangles as they construct a right triangle using Cabri Jr. Learners find the midpoint of the hypotenuse and construct a line from the midpoint to the vertex of the right angle. They then...
Curated OER
Investigating Segments in a Triangle
Pupils investigate segments in a triangle by constructing a triangle using Cabri Jr. They construct segments within the triangle that lie on the midpoints of the triangle's sides. Learners then compare the slope of base of the triangle...
EngageNY
Mid-Module Assessment Task: Grade 8 Module 2
It's time for a concept check! Check for student understanding over the three types of rigid transformations. The assessment follows the first 10 lessons in this series and to test pupils' proficiency of these concepts. Individuals...
Curated OER
Similar and Congruent Triangles
Students create and classify different types of triangles using an online geo-board. They explore the concepts of similar and congruent as they discover how to draw similar and congruent triangles.
Curated OER
Triangles in Architecture
Students find triangles in the real world. In this geometry activity, students analyze and identify properties of two and three-dimensional objects. They differentiate between similarity and congruence.
Mathematics Vision Project
Similarity and Right Triangle Trigonometry
Starting with similar triangles and dilation factors, this unit quickly and thoroughly progresses into the world of right triangle features and trigonometric relationships. Presented in easy-to-attack modules with copious application...
Curated OER
Exploring the Centroid of a Triangle
Pupils examine the centroid of a triangle as they use Cabri Jr. to construct a triangle and its medians. The dynamic nature of the software allows learners to measure the lengths of the segments in the triangle and conjecture and verify...
Mathematics Vision Project
Module 3: Polynomial Functions
An informative module highlights eight polynomial concepts. Learners work with polynomial functions, expressions, and equations through graphing, simplifying, and solving.
Curated OER
Investigating Lengths of Segments in a Triangle
Pupils explore the midsegment of a triangle in the geometry lesson. They draw and measure the segment joining the midpoints of the two sides of a triangle and compare its length to the length of the third side of the triangle. The...
Curated OER
Special Right Triangles
Young scholars identify different types of special right triangles. In this geometry lesson, students differentiate between right triangles and isosceles triangles. they construct the triangles using geometry software and make...
Curated OER
Congruent Triangles
Young scholars identify properties of triangles. In this geometry lesson, students differentiate between similar and congruent triangles. They use the umber of sides to help define the angle of the polygon.
Curated OER
Triangle Congruence
Students use web applet to create congruent triangles. In this geometry lesson, students differentiate between congruent and similar. They create shapes online and drag those shapes around to create visuals of triangles.
Curated OER
Concurrent Lines in Triangles
Students explore the concept of concurrent lines in triangles. For this concurrent lines in triangles lesson, students work in groups to investigate properties of concurrent lines in acute, right, and obtuse triangles. Students use a...
Curated OER
Similar Triangles - Applied Problems
Students differentiate between similar and congruent triangles. For this geometry lesson, students identify the angles of triangles using the similarity theorem. They apply concepts of triangles to the real world.