West Contra Costa Unified School District
Congruent and Similar Polygons
What's similar about congruent and similar polygons? Young mathematicians first measure the side lengths and angles of given figures. They use these measurements to determine relationships between side lengths and angles of congruent and...
Utah Education Network (UEN)
Finding Missing Lengths of Similar Triangles
Middle and high schoolers explore the properties of similar triangles. In this geometry lesson, pupils play a similarity basketball game, sketch similar triangles, and find the missing measures of similar figures. They find the height of...
Virginia Department of Education
Pythagorean Theorem
Investigate the meaning of the Pythagorean Theorem through modeling. After comparing the area of the square of each side, individuals cut triangles and squares to facilitate the comparison.
Virginia Department of Education
Properties of Quadrilaterals
What type of quadrilateral is that? Discover the difference between the types of quadrilaterals. Small groups investigate types of quadrilaterals using geometry software to find their properties. To keep track of the different...
Curated OER
Why Does ASA Work?
Your geometry learners explore Angle-Side-Angle congruence in this collaborative task. The sum of the interior angles of all triangles being one hundred eighty degrees, is the key learners will discover as they explain their reasoning...
Curated OER
Angles and Transversals
Pupils explore the concept of angles and transversals. They construct parallel and non-parallel lines cut by a transversal using Cabri Jr. Learners then determine which angles are congruent and the relationship of angles when two lines...
Curated OER
Finding the Area of an Equilateral Triangle
The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...
Everyday Mathematics
Mathematics Within: Slope and Triangles
Learners discover a method for determining the slope of a line by creating and comparing similar triangles. They fold coordinate grids to make three similar triangles then measure the sides to compare the relationships between the...
Willow Tree
The Pythagorean Theorem
There isn't a more popular geometry formula than the Pythagorean Theorem! Learners understand the special side relationships in a right triangle. They use the Pythagorean Theorem to find missing sides and to solve problems. They begin...
Illustrative Mathematics
Grandfather Tang's Story
It's amazing the complex figures that can be made using only a few simple shapes. Following a class reading of the children's book Grandfather Tang's Story by Ann Tompert, young mathematicians use sets of tangrams to create models of the...
Illustrative Mathematics
Placing a Fire Hydrant
Triangle centers and the segments that create them easily become an exercise in memorization, without the help of engaging applications like this lesson. Here the class investigates the measure of center that is equidistant to the three...
Curated OER
Geometry Practice: Area of Polygons #8
In this area of polygons worksheet, students solve 7 short answer and multiple choice questions about area. Students find the area of triangles given base and height, or points in the coordinate plane.
Curated OER
Searching for Angles and Lines
Students work to find and reinforce concepts related to lines and angles. They identify the characteristics of shapes that have one, two, and three dimensions. The students also work on definitions related to the geometry of shapes.
Curated OER
Angles and Similarity
Students identify triangles as similar or congruent. In this geometry lesson plan, students drag triangles around on the navigator to see the effect of different angles on the shape of the triangle. They discuss angle similarity and...
Curated OER
Scale
Students apply concepts of scales to solve problems. In this geometry instructional activity, students solve real world problems using scales, proportions and ratios. They predict the actual size of a model given the scale drawings.
Curated OER
Congruent Triangles
Tenth graders explore congruent triangles. In this geometry activity, 10th graders investigate the conditions necessary to prove two triangles are congruent by SSS, ASA, AAS, or SAS.
Curated OER
Investigating Area and Perimeter of Polygons.
Student sinvestigate the area and perimeter of polygons. They differentiate between similar and congruent polygons.. They identify the ratio and proportions of the sides and angles of polygons.
Curated OER
Battle Shapes
Fifth graders play Battleshapes which is a variation of Battleship with geometry. In this geometry lesson, 5th graders get a graph paper with four quadrants. They call out coordinate points and attempt to sink their opponents shapes.
Curated OER
Triangle Sum Theorem
Tenth graders investigate the theorems of angles and lines to prove triagle sum theorem. In this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two...
Curated OER
Symmetry
Students explore symmetry. In this geometry lesson plan, student identify and define bilateral symmetry, radial symmetry, pentagonal symmetry, hexagonal symmetry, and cubic symmetry. Students construct examples of these types of symmetry...
Curated OER
Parallelism in Our Everyday World: Parallel Lines and Beyond
Learners broaden their outlook on geometry in their everyday environment. They explore the properties of parallel lines and parallelograms and discover ways to prove the existence of parallel lines and discuss the concept of parallel lines.
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...
Alabama Learning Exchange
Creating a Reflection
Investigate geometric reflections in this geometry instructional activity. Create geometric reflections that show the reflection across the x and y axis of a coordinate graph. Learners watch a teacher demonstration before proceeding on...
Curated OER
Exploring the Hinge Theorem
Pupils explore the application of Hinge Theorem. In this geometry lesson, students write inequalities, given two sides of a triangle. They solve problems with triangular inequalities using the proper theorem.