Curated OER
Congruent Triangles
In this geometry worksheet, 10th graders identify the corresponding parts of congruent triangles.  The one page worksheet contains four problems.  Answers are not provided. 
Curated OER
Similar Triangles
Ninth graders find the height of every day objects using techniques learned through postulates that allow triangles in a problem to be similar. They calculate the length of a missing side and solve proportions.
Curated OER
Geometry of Triangles - Week 6
In this geometry of triangles worksheet, students find the length of sides, are, and angle measurement of inscribed triangles, pentagons, and midpoint of a line.  This two-page worksheet contains seven problems.
Curated OER
Similar Triangles - Applied Problems
High schoolers differentiate between similar and congruent triangles. In this geometry instructional activity, students identify the angles of triangles using the similarity theorem. They apply concepts of triangles to the real world.
Curated OER
Triangles in Architecture
Students find triangles in the real world. In this geometry lesson plan, students analyze and identify properties of two and three-dimensional objects. They differentiate between similarity and congruence.
Curated OER
The Isosceles Triangle Problem
In this geometry activity, 10th graders solve a problem involving an isosceles triangle.  The problem appears to be deceptively easy, but instead requires the use of trigonometry to arrive at a correct solution.  The one page...
Curated OER
NON-EUCLIDEAN GEOMETRY.
Students study relationships between angles, side lengths, perimeters, areas and volumes of similar objects. For this lesson students also create and critique inductive and deductive arguments concerning congruency, similarity and the...
Curated OER
Isosceles Triangles
Pupils investigate triangles. In this shapes geometry lesson, students define and state the attributes for equilateral, scalene, and isosceles triangles. Pupils locate the prefix "tri" in a variety of words and make connections with the...
Curated OER
Geometry
Students are introduced to the basics of Geometry.  Using cutout shapes, they identify whether they are polygons by using the properties of polygons.  They practice drawing shapes they are going to be using on an everyday basis and...
Curated OER
Similar Triangles
Students differentiate between similar and congruent triangles. For this geometry lesson, students identify the missing side and angle of a triangle. They identify the different ratio and proportion of the sides of a triangle.
Futures Channel
Folding Circles
Students investigate properties of circles. In this geometry lesson plan, students differentiate between similarity and congruence as they observe polygons. They investigate properties of two and three dimensional shape.
Curated OER
Slides, Flips. Turns......It's All On A Memory Book Page
Fourth graders use tangram sets to investigate the congruence of shapes. They use congruent shapes to demonstrate the properties of slides, flips, and turns. They complete a math journal entry that describes and illustrates each concept.
Curated OER
Group Isomorphisms
Students identify and apply properties of triangles. In this geometry lesson, students define equilateral triangles by sides and angles. They build cardboard triangles as they study properties of triangles.
Mathed Up!
Loci and Constructions
A General Certificate of Secondary Education math review has class members make basic constructions. Using a protractor and a ruler along with a compass, pupils develop drawings of triangles with given measurements. Scholars use their...
Illustrative Mathematics
Reflections and Isosceles Triangles
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...
Curated OER
The Centroid of a Triangle
Students familiarize themselves with the construct and measure menus. They demonstrate how to use the Sketchpad Calculator. They draw a triangle and construct the centroid. They shade in each of the small triangles and measure the area.
Curated OER
Quilting Geometry
Study geometry through the concept of quilt design. High schoolers examine the geometric shapes in various quilts and then create their own quilts using geometric shapes that fit together. In the end, they write a paragraph to...
Curated OER
Transformational Geometry Using the Geometer's Sketchpad
Middle schoolers complete a webquest on the various types of symmetry. Using a computer, they explore the concepts of transformational geometry and identify points, segments, lines and planes. They experiment with the rotation of a...
PBS
Accessible Shapes
All the 2-D and 3-D measurement work you need is in one location. Divided into three sections, the geometry lesson plans consist of visualization of three dimensions, classifying geometric figures, and finding surface area and volume....
Curated OER
Why Does SAS Work?
Your geometry learners are guided by questions that help them use the language of reflections to explain the Side-Angle-Side congruence between two triangles in this collaborative task. Given a sample solution, declaring the...
Curated OER
Congruent Triangles
Tenth graders explore congruent triangles.  In this geometry lesson, 10th graders investigate the conditions necessary to prove two triangles are congruent by SSS, ASA, AAS, or SAS. 
Curated OER
Similar Triangles on the Coordinate Plane
Students investigate triangles and their properties. In this geometry lesson, students differentiate between similar and congruent triangles. They use the SSS theorem to help identify the triangles that are similar or congruent.
Curated OER
Investigating Trigonometric Ratios Through Similar Right Triangles
Students identify similar and congruent right triangles. In this geometry lesson, students use trigonometric ratios to identify missing sides and angles of a triangle. They differentiate similar and congruent triangles.
Curated OER
Constructing Midsegments of Triangles
Students construct midsegments. In this geometry lesson, students make conjectures and apply properties of triangles to solve problems. They complete an activity on the computer.