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Lesson Plan
Curated OER

Inequalities and Triangles

For Teachers 9th - 10th
Students prove and apply theorems of triangle inequality and hinge theorem. In this geometry lesson, students will discuss which triangle is bigger and why. They will use theorems, such as Exterior Angle Inequality or the Pythagorean...
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Lesson Plan
EngageNY

Review of the Assumptions (part 1)

For Students 9th - 10th Standards
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...
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Lesson Plan
Shodor Education Foundation

Cross Sections

For Teachers 7th - 12th Standards
Use this activity on cross-sections of three-dimensional shapes in your math class to work on algebra or geometry Common Core standards. The lesson includes a list of relevent terminology, and a step-by-step process to illustrate the...
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Lesson Plan
EngageNY

Law of Sines

For Teachers 11th - 12th Standards
Prove the Law of Sines two ways. The ninth segment in a series of 16 introduces the Law of Sines to help the class find lengths of sides in oblique triangles. Pupils develop a proof of the Law of Sines by drawing an altitude and a second...
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Lesson Plan
EngageNY

The Converse of the Pythagorean Theorem

For Teachers 8th Standards
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...
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Lesson Plan
EngageNY

Scale Factors

For Students 9th - 10th Standards
Is it bigger, or is it smaller—or maybe it's the same size? Individuals learn to describe enlargements and reductions and quantify the result. Lesson five in the series connects the creation of a dilated image to the result. Pupils...
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Lesson Plan
Curated OER

Getting it Right! An Investigation of the Pythagorean Theorem

For Teachers 5th - 8th
In order to learn about the Pythagorean Theorem, young mathematicians investigate relations and patterns between different sides of a right triangle to look for possible relations among the squared sides. Once they have established the...
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Lesson Plan
Curated OER

Pythagorean Theorem by Graphic Manipulation

For Teachers 7th - 9th
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...
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Lesson Plan
Curated OER

Special Segments in a Triangle

For Teachers 10th
In this geometry worksheet, 10th graders review the vocabulary associated with the special segments of a triangle and the associated points of concurrency and solve problems in which they find the indicated missing angle or segment.  The...
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Lesson Plan
EngageNY

Prove the Pythagorean Theorem Using Similarity

For Students 9th - 10th Standards
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.
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Lesson Plan
EngageNY

The Volume of Prisms and Cylinders and Cavalieri’s Principle

For Teachers 9th - 10th Standards
Young mathematicians examine area of different figures with the same cross-sectional lengths and work up to volumes of 3D figures with the same cross-sectional areas. The instruction and the exercises stress that the two figures do not...
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Lesson Plan
EngageNY

Arcs and Chords

For Teachers 9th - 10th Standards
You've investigated relationships between chords, radii, and diameters—now it's time for arcs. Learners investigate relationships between arcs and chords. Learners then prove that congruent chords have congruent arcs, congruent arcs have...
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Lesson Plan
EngageNY

The Volume Formula of a Sphere

For Teachers 9th - 10th Standards
What is the relationship between a hemisphere, a cone, and a cylinder? Using Cavalieri's Principle, the class determines that the sum of the volume of a hemisphere and a cone with the same radius and height equals the volume of a...
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Lesson Plan
West Contra Costa Unified School District

Law of Sines

For Teachers 9th - 12th Standards
Laws are meant to be broken, right? Learners derive the Law of Sines by dropping a perpendicular from one vertex to its opposite side. Using the Law of Sines, mathematicians solve for various parts of triangles.
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Lesson Plan
EngageNY

The Power of Algebra—Finding Pythagorean Triples

For Students 10th - 12th Standards
The Pythagorean Theorem makes an appearance yet again in this instructional activity on polynomial identities. Learners prove a method for finding Pythagorean triples by applying the difference of squares identity. 
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Lesson Plan
EngageNY

Angle Sum of a Triangle

For Students 8th Standards
Prove the Angle Sum Theorem of a triangle using parallel line and transversal angle relationships. Pupils create a triangle from parallel lines and transversals. They find angle measures to show that the angles of a triangle must total...
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Lesson Plan
Curated OER

Investigating Area Using Tangrams

For Teachers 10th
Tenth graders connect the history of geometry to problem solving. In this geometry lesson, 10th graders investigate polygons through hands on manipulatives and solve problems relating to parallelograms and triangles. They calculate the...
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Lesson Plan
Curated OER

Proving the Pythagorean Theorem

For Teachers 9th - 11th
Students solve problems using the pythagorean Theorem. In this geometry lesson, students complete proofs using the Pythagorean Theorem. They share their proofs and solutions with their classmates and family members.
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Lesson Plan
Curated OER

Which Quadrilateral Is It?

For Teachers 9th - 12th
Young scholars prove conjectures about geometric figures on the plane or in space using coordinate geometry. They develop fluency in operations with real numbers, vectors and matrices using mental computation or paper-and-pencil...
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Lesson Plan
Curated OER

Distance Formula

For Teachers 1st - 11th
Learners calculate the distance between two points using the distance formula. In this geometry lesson, students derive the distance formula using the Pythagorean Theorem.
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Lesson Plan
Curated OER

Regular Polyhedra

For Teachers 10th
Tenth graders investigate the history of geometry and its different shapes. In this geometry lesson, 10th graders practice seeing three dimensional shapes and explain why there are only five polyhedra. They relate all the new materials...
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Lesson Plan
Curated OER

Why Doesn't SSA Work?

For Teachers 10th - 11th
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.
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Lesson Plan
Curated OER

Parallel and Perpendicular Lines

For Teachers 10th
Tenth graders explore parallel and perpendicular lines.  In this geometry lesson, 10th graders investigate the relationships associated with parallel lines and transversals, perpendicular lines, and the angles formed by these lines. ...
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Lesson Plan
Curated OER

Proving that You Have Found the Minimum

For Teachers 10th
Tenth graders pretend to set up an ice cream shop in a make believe town of shapes.  In this geometry lesson, 10th graders work together to put up an ice cream stand in an ideal location and solve for the minimum given the shapes.

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