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...
Curated OER
Toothpick Triangles
Learners draw a chart (included in the lesson) to use with their investigation. They review terminology of triangles and receive toothpicks to use in the lesson. Beginning with three toothpicks, students form a triangle. They complete...
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
Geometric Properties
Young scholars find triangular angles using the angle theorem. In this geometry lesson, students describe labeled triangles, use the pythagorean theorem, and rewrite information about triangles in standard form.
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,...
Curated OER
Constructions Triangles
Learners explore the difference between a construction and a drawing. They focus on various ways to construct different types of triangles. The activity is an application of Cabri Jr. and reinforces the difference between a constructions...
Curated OER
Reflections and Equilateral Triangles II
Given the lines of symmetry in an equilateral triangle, your learners find where the pre-image vertices are mapped onto the new image. They explore the properties of equilateral triangles, the impact of reflections, and the...
Curated OER
Triangle Inequality Theorem
Students use the inequality theorem to solve triangles and their properties. In this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...
Curated OER
Obtuse Triangles
Fourth graders explore obtuse triangles. In this geometry instructional activity, 4th graders make obtuse triangles with paper and scissors. They determine how to find the center of their triangle.
Curated OER
Review of Triangles
Learners investigate the Pythagorean Theorem. In this geometry lesson, students define angles and sides of right triangles. They calculate the area and surface area using formulas derived by the Pythagorean Theorem.
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...
Curated OER
Triangle Classification
Students classify different types of triangles. In this geometry lesson plan, students identify and use properties of triangles. They differentiate between isosceles and equilateral triangles.
Curated OER
Angles in Triangles
Eighth graders translate word problems using mathematical ideas. In this geometry lesson plan, 8th graders identify angles of triangles using equations and the triangle sum theorem. They create angles with a protractor and straight edge.
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
Angle-Side Relationships
Students calculate the different sides and angles of a triangle. In this geometry lesson, students use triangular properties to define the relationship between two triangle. They identify missing angles using the interior angle theorem.
Beacon Learning Center
The Fun Polygon
Junior geometers use hands-on manipulatives to explore and describe the properties and attributes of a fundamental polygon, the triangle. They learn different kinds of angles and their measurements. This well-written lesson plan provides...
Curated OER
Inscribing a Hexagon in a Circle
This activity is a follow-on activity to inscribing a square in a circle. The overall problem is more complex. It deals with geometric constructions, properties of triangles, and regular hexagons. The final part of the activity...
Curated OER
Pythagorean Theorem
Pupils find the different ratios of a triangle. In this geometry activity, students use the Pythagorean Theorem to solve for missing sides and angles on a right triangle. They use a robot to create a right triangle.
Curated OER
Pythagorean Theorem
Students explore the history of Pythagoras and his contributions to mathematics. In this middle school geometry lesson, students use one inch tiles to investigate the Pythagorean Theorem and to find the length of the sides of a right...
Curated OER
Pythagorean Theorem
Students investigate the properties and idea of the Pythagorean Theorem. In this algebra lesson, students identify the different parts of a right triangle and relate it to the Pythagorean Theorem. They do a robotic experiment to...
Curated OER
Introducing Powers and Models
Students construct two dimensional models to illustrate squared numbers. In this geometry lesson, students use graph paper and an x/y axis to build squares exponentially. Students identify powers and relationships between various figures...