Virginia Department of Education
Similar Triangles
Pupils work in pairs to investigate what it takes to prove that two triangles are similar. They work through various shortcuts to find which are enough to show a similarity relationship between the triangles. Small groups work with the...
EngageNY
The Angle-Angle (AA) Criterion for Two Triangles to Be Similar
What do you need to prove triangles are similar? Learners answer this question through a construction exploration. Once they establish the criteria, they use the congruence and proportionality properties of similar objects to find...
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...
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.
EngageNY
More About Similar Triangles
Determine whether two triangles are similar. The lesson presents opportunities for pupils to find the criterion needed to show that two triangles are similar. Scholars use the definition of similarity to find any missing side...
Mathalicious
Been Caught Stealing
You're safe, when calculating the odds of stealing second base! Learners compare the rate of a runner to the distance the ball travels, in a lesson that explores right triangles and measurement. Full of discussion questions and fun...
Curated OER
You Can't Go Wrong with a Right Triangle 2
Upper graders use the properties of right angle trignonmetry to measure objects such as the school flagpole. They solve real world problems using these properties.
EngageNY
Comparing the Ratio Method with the Parallel Method
Can you prove it? Lead your class through the development of the Side Splitter Theorem through proofs. Individuals connect the ratio and parallel method of dilation through an exploration of two proofs. After completing the proofs,...
EngageNY
Families of Parallel Lines and the Circumference of the Earth
How do you fit a tape measure around the Earth? No need if you know a little geometry! Pupils begin by extending their understanding of the Side Splitter Theorem to a transversal cut by parallel lines. Once they identify the...
Curated OER
Similar Triangles - Applied Problems
High schoolers differentiate between similar and congruent triangles. In this geometry lesson plan, students identify the angles of triangles using the similarity theorem. They apply concepts of triangles to the real world.
Curated OER
Pythagorean Theorem
Students solve problems using the Pythagorean Theorem. In this geometry instructional activity, students identify different parts of a right triangle. They use the Pythagorean Theorem to calculate missing angles and sides.
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
The Right Stuff
Learnersare introduced to the Pythagorean Theorem by exploring right triangles and the squares built on each side. They apply the Pythagorean Theorem to real-world problems. Students u se informal and nonformal arguments of proof (i.e.,...
Curated OER
Side Splitter Triangles
Students investigate the side splitter theorem. For this geometry lesson, students estimate and solve problems dealing with ratios and proportions. They identify angles created by lines that are parallel.
Curated OER
Similarity and Congruence
Students determine that two figures are similar or congruent by
investigating figures that are similar and figures that are congruent. They prove that two figures are similar or congruent by using definitions,
postulates, and theorems.
Curated OER
The Diagonal Of A Box
Students solve problems using the pythagorean theorem. They use critical thinking skills in order to use a systematic process to solve the problem. Upon solving each problem the uniqueness of the lesson is asking students to give an...
Curated OER
As the Bird Flies
Pupils investigate the properties of lines and congruent triangle theorems as well as apply geometric properties and relationships to real-world mathematical problems. Given two different scenarios, they examine maps that have been...
Curated OER
Congruence with Robot Gobot
Students identify the properties of solids and polygons. In this geometry lesson, students identify the different measurements of a triangle. They use congruence parts and theorem to prove their answer.
Alabama Learning Exchange
"I Saw the Sine"
Discover trigonometric ratios that complement each other. Using two videos, the lesson plan introduces the trigonometric ratios. The class discovers the relationship between the sine and cosine of complementary angles.
Mathematics Assessment Project
Modeling Motion: Rolling Cups
Connect the size of a rolling cup to the size of circle it makes. Pupils view videos of cups of different sizes rolling in a circle. Using the videos and additional data, they attempt to determine a relationship between cup...
Curated OER
Angles and Similarity
Students identify triangles as similar or congruent. In this geometry lesson, 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 angle...
Curated OER
Geometry Exploration Basic Trig Functions
Tenth graders solve for missing sides on a triangle using the Pythagorean Theorem. For this geometry lesson, 10th graders are introduced to basic trigonometry functions as they solve problems of right triangles. They discuss the...
Curated OER
Math Challenge
Students challenge their math knowledge through a series of lessons designed to engage critical thinking and reasoning skills. In these problem solving lessons, students work with the Pythagorean Theorem, time zones in different regions...
Curated OER
Sin, Cos and Tangent
Students find the identity o sine, cosine and tangent. In this precalculus instructional activity, students solve and identify the different parts of a right triangle. They use the ratios of the Pythagorean Theorem to find the missing...