Illustrative Mathematics
Joining Two Midpoints of Sides of a Triangle
Without ever using the actual term, this exercise has the learner develop the key properties of the midsegment of a triangle. This task leads the class to discover a proof of similar triangles using the properties of parallel...
Curated OER
Logical Relationship of Postulates & Theorems
In this postulates and theorems worksheet, students explore a concept map containing information about angles and sides, alternate interior angles, and diagonals of a parallelogram. They use the concept map to prove theorems...
Mt. San Antonio Collage
Congruent Triangles Applications
Triangles are all about threes, and practicing proving postulates is a great way to get started. The first page of the worksheet provides a brief introduction of the different properties and postulates. The remaining pages contain...
Curated OER
Congruent Triangles Postulates
Young scholars discover three lettered postulates that prove triangles congruent.
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...
Curated OER
Visual Structures of Postulates and Axioms in Algebraic Operations
Students investigate Axioms and Postulates. In this proof and linear transformation of equations lesson, students explore axioms and postulates to solve linear equations. Students construct game cards to analyze the linear transformation...
Curated OER
More Congruent Triangles
In this congruent triangles worksheet, 10th graders solve 5 various types of geometry problems related to triangles. First, they draw and label triangles, indicating the additional pairs of corresponding parts that would have to be...
Curated OER
Geometry Practice: G.G. 28 #2: Triangle Congruence
In this triangle congruence learning exercise, students use SSS, ASA, AAS and HL to determine the congruence of triangles. They identify the theorem that proves congruence. This three-page learning exercise contains 4...
Curated OER
Self-Check for Triangle Congruence Proofs Multiple Choice
In this triangle congruence worksheet, students select the postulate that is being illustrated to prove congruence between triangles. The worksheet is self-scoring. Once students select the "check your work" link, they are given their...
Virginia Department of Education
High School Mathematics Geometry Vocabulary Word Wall Cards
Having a good working knowledge of math vocabulary is especially important for geometry learners. Here are 119 pages worth of wonderfully constructed definitions, constructions, formulas, properties, theorems, and postulates. This is a...
Curated OER
Proving Triangles Congruent
In this proving triangles congruent worksheet, 10th graders solve 5 different problems that include proofs and proving congruence in triangles. First, they determine which postulate can be used to prove the triangles congruent and mark...
West Contra Costa Unified School District
Investigating Similar Triangles
Let your use of the resource be in proportion to its usefulness. Pupils investigate similar triangles by measuring side lengths and considering given angle measures. The results of the investigation help develop generalizations about...
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...
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
More Congruent Triangles
In this congruent triangles worksheet, 10th graders solve 6 various forms of problems that include a proof and a word problem. First, they draw and label triangles and indicate the additional pairs of corresponding parts that would have...
Curated OER
Triangle Inequality Theorems Investigation
Young scholars estimate and measure triangles. In this geometry lesson, students identify the relationship between three sides and a triangle. They use the inequality theorem to decide if a triangle will be formed or not.
Mathematics Vision Project
Geometric Figures
Logical thinking is at the forefront of this jam-packed lesson, with young mathematicians not only investigating geometric concepts but also how they "know what they know". Through each activity and worksheet, learners wrestle with...
Virginia Department of Education
Congruent Triangles
Is this enough to show the two triangles are congruent? Small groups work through different combinations of constructing triangles from congruent parts to determine which combinations create only congruent triangles. Participants use the...
Curated OER
Proofs with Triangles Self-check Practice
In this triangle theorems activity, students identify the theorem used to prove the specified triangular relationship. Students are shown an illustration of two or more triangles. They identify the postulate that would be used to prove...
Curated OER
Congruent Triangles
High schoolers explore the concept of congruent triangles. In this congruent triangles lesson, students use Cabri Jr. to construct two congruent triangles using circles. High schoolers determine if the two triangles are...
National Institute of Open Schooling
The Gaseous State
Sixth in a series of 36, this lesson focuses on gases and their behavior in given situations. Learners review the states of matter and then focus on gases, specifically learning Boyle's, Charles's, Avogadro's Laws, Dalton's, and Graham's...
National Institute of Open Schooling
Coordination Compounds
Cyanide, a coordination compound, is used in the extraction of gold and silver. Part 24 in the series of 36 delves into the world of coordination compounds. Classes learn, through readings, discussions, and answering questions, how to...
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
CSI Investigation of Congruence and Similarity
Students differentiate between similarity and congruence using polygons. In this geometry lesson plan, students label triangles based on their properties. They find missing sides and angles using the interior sum theorem.