Geometric Proof Teacher Resources

Find Geometric Proof lesson plans and worksheets
Showing 49 - 72 of 152 resources
Lesson Planet

Coordinate Proofs

For Students 8th - 11th Standards
How do you know you know? Prove it! The guide goes through several examples and includes a link to a video to teach learners how to work through coordinate proofs. The goal is to prove that different shapes are indeed that shape. 
EngageNY

Triangle Congruency Proofs (part 1)

For Teachers 9th - 10th Standards
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...
1 In 1 Collection
EngageNY

Informal Proofs of Properties of Dilations

For Teachers 8th Standards
Challenge the class to prove that the dilation properties always hold. The lesson develops an informal proof of the properties of dilations through a discussion. Two of the proofs are verified with each class member performing the...
1 In 1 Collection
EngageNY

Informal Proof of the Pythagorean Theorem

For Students 8th Standards
Prove the Pythagorean Theorem using multiple informal proofs. Scholars first develop an understanding of the origins of the Pythagorean Theorem through proofs. They round out the lesson by using the theorem to find missing side lengths...
EngageNY

Triangle Congruency Proofs (part 2)

For Teachers 9th - 10th Standards
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...
Lesson Planet

Inscribed Quadrilaterals

For Students 9th - 12th Standards
Take a supplementary look at quadrilaterals. Scholars develop a proof to show that opposite angles of a quadrilateral inscribed in a circle are supplementary. To finish, they investigate a different quadrilateral to see whether they can...
Lesson Planet

Justifying a Proof of the AA Similarity Theorem

For Students 9th - 12th Standards
Why are two triangles with congruent angles similar? Class members provide the justifications or explanations of the steps of a proof of the AA Similarity Theorem. The proof uses transformations as a basis to proving the theorem.
5:17
Lesson Planet

How Many Ways Are There to Prove the Pythagorean Theorem?

For Students 8th - 12th Standards
There is more than one way to prove the Pythagorean Theorem. Euclid and Einstein found the same way to prove the Pythagorean Theorem. The video introduces several other ways to prove the theorem along with the history of its use.
7:37
Lesson Planet

Pythagorean Theorem Proofs

For Students 10th - 12th Standards
Your class knows the Pythagorean Theorem, but can they prove it? A series of three videos shows two proofs of the Pythagorean Theorem and use it to classify triangles. 
Lesson Planet

Congruent Triangles

For Teachers 9th - 11th Standards
Is this enough to show the two triangles are congruent? Small groups work through different combinations of constructing triangles from congruent parts to determine which combinations create only congruent triangles. Participants use the...
Lesson Planet

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...
EngageNY

Comparing the Ratio Method with the Parallel Method

For Students 9th - 10th Standards
Can you prove it? Lead your class through the development of the Side Splitter Theorem through proofs. Individuals connect the ratio and parallel method of dilation through an exploration of two proofs. After completing the proofs,...
1 In 1 Collection
EngageNY

Converse of the Pythagorean Theorem

For Students 8th Standards
Discover a new application of the Pythagorean Theorem. Learners prove and apply the converse of the Pythagorean Theorem in the 17th lesson in a 25-part series. The examples ask learners to verify right triangles using the converse of the...
Lesson Planet

Median Concurrence Proof

For Students 9th - 12th Standards
Develop a proof to show what appears to be true in a drawing actually is true. The assessment asks pupils to draw the three medians of a triangle. Learners develop a proof showing that the point of intersection in their drawing is...
0:53
Lesson Planet

Angles in the Same Segment – Proof

For Students 8th - 12th Standards
If angles intercept the same arc, the angles must be the same size. The quick video talks through the proof of showing the reason two inscribed angles that intersect the same arc have the same measurement. Pupils then create their own...
Lesson Planet

IGD: Dropping a Perpendicular Line

For Students 9th - 12th Standards
Discover how circles help determine a perpendicular line. Using the applet, scholars construct the perpendicular to a line from a point. The interactive allows pupils to change the position of the line and perform each step of the...
Lesson Planet

Proving a Rectangle Is a Parallelogram

For Students 9th - 12th Standards
Take the time to prove what seems obvious. The resource provides pupils a figure of a rectangle, which they use to develop a proof showing that the rectangle is also a parallelogram. Scholars must rely on the definition of a rectangle to...
EngageNY

Congruence Criteria for Triangles—ASA and SSS

For Students 9th - 10th Standards
How do you know if a pair of triangles are congruent? Use the instructional activity to help class members become comfortable identifying the congruence criteria. They begin with an exploration of ASA and SSS criteria through...
1 In 1 Collection
EngageNY

Informal Proof of AA Criterion for Similarity

For Teachers 8th Standards
What does it take to show two triangles are similar? The 11th segment in a series of 16 introduces the AA Criterion for Similarity. A discussion provides an informal proof of the theorem. Exercises and problems require scholars to apply...
Lesson Planet

Pythagorean Theorem and Converse

For Students 8th Standards
You've heard that it is true, but can you prove it? Scholars learn the Pythagorean Theorem through proof. After an overview of proofs of the theorem, learners apply it to prove triangles are right and to problem solve. This is the second...
Lesson Planet

Justifying ASA Congruence

For Students 9th - 12th Standards
Take a transformed approach to proving angle-side-angle congruence. The short assessment asks for a proof of ASA Congruence using transformations. Pupils use their knowledge of rigid motions and that congruence is preserved under them to...
Lesson Planet

Prove the AA Similarity Theorem

For Students 9th - 12th Standards
Transform a diagram into a proof. Given two triangles on a coordinate plane, pupils develop a proof to show they are similar. The learners use the fact that two angles of one triangle are congruent to two angles of another and their...
Lesson Planet

Are All Circles Similar?

For Teachers 9th - 11th Standards
Dilated pupils, the way to prove circles are similar. Using the knowledge of dilations of polygons, class members learn how to dilate a circle to show that it is similar to any other circle. The teacher guides the class through a proof...
Lesson Planet

Elementary Geometry

For Students 9th - 12th Standards
Your class may believe that geometry is a trial, but they don't know how right they are. A thorough math lesson combines the laws of logic with the laws of geometry. As high schoolers review the work of historical mathematicians and the...