Curated OER
Congruent Triangles Postulates
Students discover three lettered postulates that prove triangles congruent.
Curated OER
Congruent Triangles
High schoolers identify properties of triangles. In this geometry lesson, students differentiate between similar and congruent triangles. They use the umber of sides to help define the angle of the polygon.
EngageNY
Congruence Criteria for Triangles—ASA and SSS
How do you know if a pair of triangles are congruent? Use the lesson to help class members become comfortable identifying the congruence criteria. They begin with an exploration of ASA and SSS criteria through transformations and...
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...
Curated OER
Congruent Trianges - Is This Enough Information?
Seventh graders determine whether two triangles are congruent and provide an explanation to why they are not. They apply concepts of measurement of angles and collect evidence of congruent angles in the world.
EngageNY
Applications of Congruence in Terms of Rigid Motions
Corresponding parts, congruent parts, congruent corresponding parts—what does it all mean? The resource challenges pupils to identify corresponding parts for pairs of figures. It uses examples of figures that undergo rigid...
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...
EngageNY
More on the Angles of a Triangle
Angles and triangles: they're all connected. Uncover the connections between angles in triangles. Scholars learn how to find both exterior and interior angle measures in triangles. The lesson emphasizes the vocabulary related to these...
EngageNY
Properties of Parallelograms
Everyone knows that opposite sides of a parallelogram are congruent, but can you prove it? Challenge pupils to use triangle congruence to prove properties of quadrilaterals. Learners complete formal two-column proofs before moving on to...
Curated OER
Congruent Triangles
Tenth graders explore congruent triangles. For this geometry lesson, 10th graders investigate the conditions necessary to prove two triangles are congruent by SSS, ASA, AAS, or SAS.
Concord Consortium
Isosceles Triangle Spaces
How many different types of triangles can your class name? A discovery lesson guides learners through an exploration of the different triangle types and the relationships between their angles and sides. Using coordinate geometry,...
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 lines cut...
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
Triangle Inequality
Students discover that the sum of the lengths of any two sides of a triangle must be greater than the third side. They are shown how a triangle is formed using three strips such as that the triangle is seen inside the strips.
Curated OER
Triangle Proofs
Tenth graders complete a unit of lessons on congruent triangles and triangle proofs. They observe and participate in teacher-led discussions of examples of the methods to prove that triangles are congruent, and create an original proof.
Curated OER
Toe to Toe Geo
Students study triangles. In this triangle lesson plan, students compare and classify triangles while milling to music. Students will also trade triangles so they can match up with other similar triangles. Triangles are provided.
West Contra Costa Unified School District
Investigating Special Right Triangles
Scholars first investigate relationships in the side lengths of 30°-60°-90° triangles and 45°-45°-90° triangles. This knowledge then helps them solve problems later in the lesson about special right triangles.
Curated OER
Triangle Midsegment
Learn how to calculate the length and midsegments of triangles. Students differentiate between similar and congruent triangles. They create a spreadsheet with their findings.
Curated OER
Art or Junk? Discovering the Triangle Inequality
Middle schoolers study the triangle inequality. They will identify, compare, and analyze attributes of two and three-dimensional shapes. Then they develop vocabulary to describe the attributes. They also use manipulatives to analyze the...
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
Triangle worksheets
In this geometry worksheet, 10th graders explore triangle properties, including the sum of the measures of the angles of a triangle, the triangle inequalities, properties of isosceles triangles, properties of congruent triangles, and...
Curated OER
Using Congruent Triangles
In this geometry worksheet, 10th graders use basic knowledge of congruent triangles (CPCTC) to prove that the given triangles are congruent. The one page worksheet contains four problems. Answers are not included.
Willow Tree
Angle Sum Property of Triangles
All triangles have some things in common. Using these properties of triangles, learners find missing angle measures. Scholars use the Angle Sum Property and properties of special triangles throughout the lesson.
Charleston School District
Review Unit 2: Congruence and Similarity
Review for the test with a comprehensive list of terms and concepts for the unit on congruence and similarity. It divides divides the sections in the order of the lessons presented during the unit.