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Handout
Lockport City School District

Reasons for Geometric Statement/Reason Proofs

For Students 8th - 11th Standards
Stuck trying to remember the formal language of a geometric proof? Never fear, this handout has them all ready to go. The reasons are sectioned by topic so this handy guide is ready when you are to tackle those two column proofs. 
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Unit Plan
1
1
EngageNY

Congruence, Proof, and Constructions

For Teachers 8th - 10th Standards
This amazingly extensive unit covers a wealth of geometric ground, ranging from constructions to angle properties, triangle theorems, rigid transformations, and fundamentals of formal proofs.  Each of the almost-forty lessons is broken...
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Lesson Plan
Curated OER

Proof of the Pythagorean Theorem Using Transformations

For Teachers 9th - 12th Standards
Middle and high schoolers construct a triangle using Cabri Jr. They construct squares on each of the legs and hypotenuse of the triangle. Pupils show that the area of the squares on the leg equal the area of the square on the hypotenuse.
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Instructional Video10:17
2
2
Flipped Math

Unit 6 Review: Similar Figures

For Students 9th - 12th Standards
After a short review of the material from the Similar Figures Unit, pupils work through 18 problems to further practice the skills from the unit. Scholars apply those skills in the application problems at the end of the review.
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Instructional Video11:57
2
2
Flipped Math

Side Splitter Theorem

For Students 9th - 12th Standards
Apply perspective to similarity. Individuals learn about the Side Splitter Theorem by looking at perspective drawings. Pupils use the theorem and its corollary to find missing lengths in figures. Next, they practice using the theorem and...
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Instructional Video16:20
2
2
Flipped Math

Prove Triangles Similar

For Students 9th - 12th Standards
Show more than one way to prove similarity. Scholars learn three different methods to show two triangles are similar, Angle-Angle, Side-Side-Side, and Side-Angle-Side. Pupils practice applying these methods to determine whether two given...
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Instructional Video9:36
2
2
Flipped Math

Proving Lines Parallel

For Students 9th - 12th Standards
Show it can all be proved. Scholars learn the converses of the properties of parallel lines. Using the converses, pupils determine which lines are parallel based on angle measurements and practice using a flow proof to show that two...
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Instructional Video6:57
2
2
Flipped Math

Unit 2 Review: Reasoning and Proofs

For Students 9th - 12th Standards
The proof is in the review. Individuals watch a short review of the content from the unit to prepare for the unit exam. The review covers inductive reasoning, conditional and related statements, and two-column algebraic and geometric...
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Instructional Video16:33
2
2
Flipped Math

More with Proofs

For Students 9th - 12th Standards
Proofs may be as easy as 1, 2, 3 ... maybe. Pupils participate in creating four example proofs. The presentation uses a list of geometric properties to develop the proofs by filling in both the statements and reasons. Scholars practice...
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Instructional Video22:15
2
2
Flipped Math

Intro to Proofs

For Students 9th - 12th Standards
Prove the best way to keep up in Geometry. Scholars first review algebraic properties from Algebra. Learners then use the properties to create two-column proofs to solve linear equations before completing algebraic proofs by providing...
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Unit Plan
Radford University

Parallel Lines Cut By a Transversal

For Teachers 9th - 12th Standards
Perhaps planning a city isn't so difficult after all. Scholars first perform geometric constructions and investigate how parallel lines are useful in real-world situations. They then work on a city design project, drawing street maps,...
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Unit Plan
Radford University

Parallel Lines Cut by a Transversal

For Teachers 9th - 12th Standards
Use the parallel lines to find your way. After first reviewing geometric constructions and the relationships between angles formed by parallel lines and a transversal, young mathematicians write proofs for theorems relating to parallel...
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Instructional Video9:11
Corbett Maths

Algebraic Proof

For Students 8th - 12th Standards
Proofs do not exist only in geometry. The video shows the class different ways that proofs appear in algebra. Pupils work through a variety of algebraic proofs involving the divisibility of an algebraic expression or whether it is even...
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Unit Plan
Mathematics Vision Project

Module 3: Geometric Figures

For Teachers 9th - 12th Standards
It's just not enough to know that something is true. Part of a MVP Geometry unit teaches young mathematicians how to write flow proofs and two-column proofs for conjectures involving lines, angles, and triangles.
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Unit Plan
Mathematics Vision Project

Module 2: Congruence, Construction and Proof

For Teachers 9th - 12th Standards
Construct yourself a winning geometry unit. A set of lessons introduces geometry scholars to constructions and proofs with compasses and straightedges. It also covers triangle congruence through transformations. This is the second of...
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Assessment
Concord Consortium

Area Upgrade

For Students 10th - 12th Standards
Imagine a world built of triangles. A performance task asks scholars to consider just that. They use their knowledge of special segments of a triangle to make decisions about the area of triangular plots of land.
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Lesson Plan
Alabama Learning Exchange

Triangle Area: No Height? Use the Sine

For Students 9th - 12th Standards
No height? No problem! Learners use their knowledge and a little help from GeoGebra to develop the Law of Sines formula. The Law of Sines helps to determine the height of triangles to calculate the area.
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Interactive
Shodor Education Foundation

Squaring the Triangle

For Students 8th - 12th Standards
Teach budding mathematicians how to square a triangle with an interactive that shows a graphical proof of the Pythagorean Theorem. Pupils alter the lengths of the legs using sliders. Using the inputted lengths, the applet displays the...
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Interactive
CK-12 Foundation

Proofs: Angle Pairs and Segments—The Three Angle Problem

For Students 9th - 11th
Finding the sum of the measures of three angles is easy, unless you have no clue what the measures are. Learners use an interactive diagram to see a geometric problem in a different way. A set of challenge questions takes them through...
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Interactive
CK-12 Foundation

Parallelogram Proofs: Quadrilaterals that are Parallelograms

For Students 6th - 12th
What conditions must be met for a quadrilateral to be a parallelogram? A slider interactive allows individuals to move the vertices of a quadrilateral. They answer questions that prove whether a given quadrilateral is a parallelogram.
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Activity
Education Development Center

Proof with Parallelogram Vertices

For Teachers 8th - 10th Standards
Geometric figures are perfect to use for proofs. Scholars prove conjectures about whether given points lie on a triangle and about midpoints. They use a provided dialogue among fictional students to frame their responses.
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Activity
Education Development Center

Sum of Rational and Irrational is Irrational

For Teachers 8th - 9th Standards
Sometimes the indirect path is best. Scholars determine whether the sum of a rational number and an irrational number is irrational. Reading a transcript of a conversation between classmates leads to an indirect proof of this concept.
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Unit Plan
Mathematics Vision Project

Connecting Algebra and Geometry

For Teachers 9th - 10th Standards
Connect algebra and geometry on the coordinate plane. The eighth unit in a nine-part integrated course has pupils develop the distance formula from the Pythagorean Theorem. Scholars prove geometric theorems using coordinates including...
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Unit Plan
Mathematics Vision Project

Congruence, Construction and Proof

For Teachers 9th - 10th Standards
Learn about constructing figures, proofs, and transformations. The seventh unit in a course of nine makes the connections between geometric constructions, congruence, and proofs. Scholars learn to construct special quadrilaterals,...