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...
Illustrative Mathematics
Similar Triangles
Proving triangles are similar is often an exercise in applying one of the many theorems young geometers memorize, like the AA similarity criteria. But proving that the criteria themselves are valid from basic principles is a great...
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...
EngageNY
Unknown Angle Proofs—Proofs of Known Facts
Lead the class in a Greek history activity with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete practice...
Illustrative Mathematics
Equal Area Triangles on the Same Base II
A deceptively simple question setup leads to a number of attack methods and a surprisingly sophisticated solution set in this open-ended problem. Young geometers of different strengths can go about defining the solutions graphically,...
EngageNY
The Converse of the Pythagorean Theorem
Is it a right triangle or not? Introduce scholars to the converse of the Pythagorean Theorem with a lesson that also provides a proof by contradiction of the converse. Pupils use the converse to determine whether triangles with given...
Curated OER
NON-EUCLIDEAN GEOMETRY.
Students study relationships between angles, side lengths, perimeters, areas and volumes of similar objects. In this lesson students also create and critique inductive and deductive arguments concerning congruency, similarity and the...
EngageNY
Review of the Assumptions (part 1)
What was the property again? Tired of hearing this from your pupils? Use this table to organize properties studied and as a reference tool for individuals. Learners apply each property in the third column of the table to ensure their...
Curated OER
Pythagorean Theorem by Graphic Manipulation
There are many different ways to show a proof of the Pythagorean Theorem. Here is a nice hands-on paper cutting activity that shows a graphic representation. You can even challenge your young Pythagoreans to come up with their own...
Curated OER
Mathematics
Twelfth graders explore a variation of proof. In this geometry lesson, 12th graders apply their knowledge of proof to different scenario. They use 3 different tiers to advance through the lesson.
Curated OER
Around the World With Geometry
Learners identify shapes, create shapes, and make a pyramid, a drum, and a sail using their shapes. In this shapes lesson plan, students also identify plane and space shapes.
Curated OER
Why Doesn't SSA Work?
Students investigate the relationship between angles and their sides. In this geometry lesson, students prove why SSA does not work as a true angle side relationship theorem.
EngageNY
Three-Dimensional Space
How do 2-D properties relate in 3-D? Lead the class in a discussion on how to draw and see relationships of lines and planes in three dimensions. The ability to see these relationships is critical to the further study of volume and other...
Virginia Department of Education
Logic and Conditional Statements
If there is a conditional statement, then there is a hypothesis and conclusion. Pupils learn how to identify the parts of conditional statements. Class members continue to work with conditional statements and rewrite them in their many...
Shodor Education Foundation
Surface Area of Rectangular Prism
With this interactive lesson plan, learners compute the surface area of rectangular prisms. They visit an online investigation applet and record data on the provided handout. Pair this lesson plan with the volume lesson plan by the same...
Curated OER
Interactivate - Lines, Rays, Line Segments, and Planes
Students explore lines, rays, line segments, and planes. In this math lesson, students discuss the math concepts and direct their instructor in graphing functions. Students collaborate in graphing additional functions.
Curated OER
Inductive and Deductive Reasoning
High schoolers use logical arguments and inductive reasoning to make or disprove conjectures. After observing a teacher led demonstration, students discover that the deductive process narrows facts to a few possible conclusions. In...
Curated OER
Fractals and the Chaos Game
Students explore the concept of fractals. In this fractals lesson plan, students play the "Chaos Game" via an applet. Students place dots on the screen to recognize that they have created Sierpinski's Triangle.
Curated OER
Lines, Rays, Line Segments, and Planes
Students are introduced to lines, rays, line segments and planes and study the differences between them. They also practice graphing lines, rays, line segments and planes
Curated OER
Irregular Fractals
High schoolers explore the concept of irregular fractals. In this irregular fractals activity, students discuss how to find fractal dimensions through teacher led discussion. High schoolers calculate fractal dimensions of various fractals.