EngageNY
Special Relationships Within Right Triangles—Dividing into Two Similar Sub-Triangles
Why are right triangles so special? Pupils begin their study of right triangles by examining similar right triangles. Verifying through proofs, scholars recognize the three similar right triangles formed by drawing the altitude. Once...
EngageNY
Triangle Congruency Proofs (part 2)
Looking to challenge your students that have mastered basic triangle congruence proofs? A collection of proofs employ previously learned definitions, theorems, and properties. Pupils draw on their past experiences with proofs to...
EngageNY
Triangle Congruency Proofs (part 1)
Can they put it all together? Ninth graders apply what they know about proofs and triangle congruence to complete these proofs. These proofs go beyond the basic triangle congruence proofs and use various properties, theorems, and...
EngageNY
Perimeter and Area of Triangles in the Cartesian Plane
Pupils figure out how to be resourceful when tasked with finding the area of a triangle knowing nothing but its endpoints. Beginning by exploring and decomposing a triangle, learners find the perimeter and area of a triangle. They then...
EngageNY
Congruence Criteria for Triangles—SAS
Looking for a different approach to triangle congruence criteria? Employ transformations to determine congruent triangles. Learners list the transformations required to map one triangle to the next. They learn to identify congruence if...
Curated OER
Geo Shapes
First graders listen as the book, "Try It With Triangles" is read to the class. They name the geometric shapes that they see in the story and view the Shape Vocabulary Cards as they name them from the book. They then cut out the...
Curated OER
Napolean Triangle
Students investigate the Napoleon triangle theory. In this polygon lesson plan, students differentiate between the boundary points, interior and lattice point of a polygon. They apply concepts of equilateral triangles to solve problems.
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.
EngageNY
Prove the Pythagorean Theorem Using Similarity
Amaze your classes with the ability to find side lengths of triangles immediately — they'll all want to know your trick! Learners use the Pythagorean Theorem and special right triangle relationships to find missing side lengths.
Utah Education Network (UEN)
Geo Shapes
Invite your first graders to compose and decompose two and three-dimensional figures with this fun, hands-on instructional activity. They investigate and predict the results of putting together and taking apart two-dimensional shapes...
EngageNY
Using Trigonometry to Determine Area
What do you do when you don't think you have enough information? You look for another way to do the problem! Pupils combine what they know about finding the area of a triangle and trigonometry to determine triangle area when they don't...
EngageNY
How Far Away Is the Moon?
Does the space shuttle have an odometer? Maybe, but all that is needed to determine the distance to the moon is a little geometry! The lesson asks scholars to sketch the relationship of the Earth and moon using shadows of an eclipse....
Curated OER
Shape Up
Students explore differents types of triangles and quadriaterals. For this polygon lesson, students model identify and compare two and three dimensional geometric figures. Students create tangrams and discover the difference between...
Curated OER
Pedal Triangles
Students identify the properties and theorems of triangles. In this geometry lesson, students construct angle bisectors using a compass and straight edge. They identify triangular similarity and congruency.
Curated OER
Angles and Triangles
Eighth graders examine Jewish symbols. For this Holocaust lesson, 8th graders discuss the meanings behind the Swastika and the Star of David. Students also measure the angles and shapes with the symbols.
Curated OER
Triangle Town
Second graders create a fact family town to develop the understanding of numbers related in fact families. They learn each family has a big number and two baby numbers. They make triangle shaped houses for their facts.
Curated OER
Geo Jammin' By DeSign - Day 2, Lesson 7: Start At Square One
Students examine new shape possibilities by combining two and four triangles using manipulatives.
EngageNY
Similarity and the Angle Bisector Theorem
Identifying and verifying reproducible patterns in mathematics is an essential skill. Mathematicians identify the relationship of sides when an angle is bisected in a triangle. Once the pupils determine the relationship, they prove it to...
Curated OER
Investigating Shapes in Our World
First graders explore shapes. In this geometry lesson, 1st graders make shapes with geo-boards, use play-dough to make three-dimensional figures, and make a shape book using pre-cut shapes.
Curated OER
Formula Determination
Learners derive a formula for the interior degrees in any convex polygon. In this geometric figure lesson, students determine the shapes of various polygons and the number of triangles formed. They use this information to derive the...
Curated OER
Tessellation Trial and Error
In this interactive lesson, young scholars review attributes of equilateral polygons. They are introduced to the concept of a tessellation. Using protractors and pre-cut shapes, students arrange a variety of tiles to create...
Curated OER
Geo-Critters (Geometry Critters)
Students read the book The Math Curse by Jon Scieszka and study geometry. In this geometry lesson, students identify geometric shapes and their properties. Students create a geo-critter.
Curated OER
Plane Figures
Fifth graders create polygons requested by their teacher. In this polygons lesson, 5th graders watch a video and listen to a song about polygons. Then, students take turns labeling various polygons and practice making polygons.
Curated OER
Geo-Mat
Students review plane figures by playing a game that resembles "Twister." They listen to directions to locate a large example of the figure which is placed on the floor.