Lesson Plans and Worksheets
Browse by Subject
Isosceles Triangle Teacher Resources
Find Isosceles Triangle educational ideas and activities
Show your school spirit while proving theorems about triangles! Your student geometers are charged with coming up with a new design for the school pennant, following specific guidelines. Along the way, they need to prove the theorem that base angles of an isosceles triangle are congruent. Not only is this a learning activity, if you allow time to decorate the pennants, you'll end up with great room or hall decorations.
Geometers explore symmetries of isosceles triangles by using rigid transformations of the plane. They complete four tasks, including congruence proofs, which illustrate the relationship between congruence and rigid transformations. The activity requires a thorough understanding of the definition of reflection about a line and is better suited for more sophisticated geometry students.
Fifth graders solve problems while examining a variety of isosceles triangles. In this isosceles triangle lesson, 5th graders examine shapes to find their characteristics. Students pay particular attention to the characteristics of isosceles triangles and solve problems related to them.
Young scholars explore the concept of triangles. In this triangles lesson, students prove and apply the Isosceles Triangle Theorem using Cabri Jr. on the graphing calculator. Young scholars construct triangles and measure the angles. Students drag the points of the triangle to notice the relationship in angle measure. Young scholars construct an isosceles triangle and develop the idea that isosceles triangles have two equal sides and two congruent angles.
Students construct triangles using Cabri Jr. In this constructing triangles using Cabri Jr. lesson, students construct isosceles triangles. Students use two radii of a circle to construct an isosceles triangle. Students measure the angles of their triangle construction and make conjectures about isosceles triangles.
In this geometry worksheet, 10th graders explore triangle properties, including the sum of the measures of the angles of a triangle, the triangle inequalities, properties of isosceles triangles, properties of congruent triangles, and flowchart proofs. The eight page worksheet contains seventy-six problems. Answers are not provided.
Students investigate triangles. For this shapes geometry lesson, students define and state the attributes for equilateral, scalene, and isosceles triangles. Students locate the prefix "tri" in a variety of words and make connections with the relationship to "three." Students cut out and arrange triangles to make a picture.
The second half of a two-part study of tangrams introduces first graders to geometry. A tangram template and many ideas are useful for a primary grade lesson in flipping and rotating shapes, and using geometric shapes to create other shapes. References to a project using Photostory (video-making software you can download for free) from the first lesson inspire ideas about how to integrate language arts: have small groups tell a story illustrated with shapes they make by combining the tangram pieces. However, much of the lesson is focused on properties like congruence and similarity, angles, and parallel sides that would only be relevant to your most gifted learners or classes older than first grade. Select the best parts of the resource to use in your classroom.