Curated OER
Constructing Midsegments of Triangles
Students construct midsegments. In this geometry lesson, students make conjectures and apply properties of triangles to solve problems. They complete an activity on the computer.
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...
Illustrative Mathematics
Are They Similar?
Learners separate things that just appear similar from those that are actually similar. A diagram of triangles is given, and then a variety of geometric characteristics changed and the similarity of the triangles analyzed. Because the...
Curated OER
Congruent Triangles
Students 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.
Curated OER
Equilateral Triangles
Students examine the attribute of equilateral triangles. In this equilateral triangle lesson, students examine a number of paper triangles to determine how they are classified. They determine how triangles are depicted in Navajo rugs.
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
Reflections and Equilateral Triangles
Your learners collaboratively find the lines of symmetry in an equilateral triangle using rigid transformations and symmetry. Through congruence proofs they show that they understand congruence in terms of rigid motions as they...
Charleston School District
Pre-Test Unit 2: Similar and Congruent
A pre-test contains questions about transformations that lead to congruent and similar images. It also covers angle relationships associated with triangles and parallel lines intersected by a transversal.
Mathed Up!
Congruent Shapes
Are congruent shapes compatible? Congruent shapes are identical to one another, and throughout the assessment, young mathematicians identify given shapes as congruent.
West Contra Costa Unified School District
Congruence Through Transformations
Transform your lesson on transformations. Learners use given congruent triangles and tracing paper to determine the single transformation that carries one to the other. The concept is extended to combinations of transformations to...
Mathematics Assessment Project
Circles in Triangles
Circles, and triangles, and tangents, oh my! In the assessment task, learners first answer questions leading to the radius of an inscribed circle for a given right triangle. They then use the result to independently determine the...
Curated OER
Tile Patterns II: Hexagons
After learning that the sum of interior angles for triangles is 108 degrees, take it further to show that the sum of angles in any polygon is the same! Using hexagons, pupils practice finding the measure of the six congruent angles. Make...
Cord Online
Pyramids and Cones
Young mathematicians find the surface area and volume of a square pyramid and a cone. In what looks like a typical activity out of a textbook, you'll find an activity where learners find an unknown measurement of a pyramid or...
Curated OER
Visualize Triangles
In this finding triangles in parallelograms activity, students observe parallelograms, visualize half as congruent to triangles, and choose the triangle that would match each one. Students solve 5 problems.
Curated OER
The Value of Volume
Students measure the perimeter and area of their polygons. In this geometry lesson, students calculate the volume and area using the correct tools. They calculate the time and temperature and the perimeter and side lengths of triangles.
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...
Curated OER
Triangle Congruence
Students use web applet to create congruent triangles. In this geometry lesson, students differentiate between congruent and similar. They create shapes online and drag those shapes around to create visuals of triangles.
Curated OER
Slides, Flips. Turns......It's All On A Memory Book Page
Fourth graders use tangram sets to investigate the congruence of shapes. They use congruent shapes to demonstrate the properties of slides, flips, and turns. They complete a math journal entry that describes and illustrates each concept.
Curated OER
Group Isomorphisms
Students identify and apply properties of triangles. In this geometry lesson, students define equilateral triangles by sides and angles. They build cardboard triangles as they study properties of triangles.
Curated OER
Nested Similar Triangles
Nested triangles have been created so that they share a common vertex and vertex angle. Learners drag the endpoints of the side that is opposite the common angle to discover the conditions that make the nested triangles similar. When...
Improving Measurement and Geometry in Elementary Schools
The Sum of the Interior Angles of a Polygon
Junior geometers discover that polygons can be decomposed into triangles and that the number of triangles can be determined by a rule. Note that the Geometer’s Sketchpad® software is required to carry out all components of this...
Curated OER
Triangles
In this triangles instructional activity, 10th graders solve 3 extensive informal geometry problems that involve triangles. First, they sketch a triangle, selecting 3 of the sides and constructing 3 midpoints. Students then draw each of...
Illustrative Mathematics
Why Does SSS Work?
While it may seem incredibly obvious to the geometry student that congruent sides make congruent triangles, the proving of this by definition actually takes a bit of work. This exercise steps the class through this kind of proof by...
EngageNY
Using Unique Triangles to Solve Real-World and Mathematical Problems
How can congruent triangles help mark a soccer field? This is just one question your classes can answer after solving the real-world problems in the lesson plan. Each example posed through a word problem elicits higher-order thinking and...