Geometric Proof Teacher Resources

Looking for a different approach to triangle congruence criteria? Employ transformations to determine congruent triangles. Learners list the transformations required to map one triangle to the next. They learn to identify congruence if...

It's time to prove one's knowledge of triangle congruence proofs. Scholars watch a video to review triangle classifications and how to use properties of triangles to set up and solve equations for missing values. They also review the...

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...

Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...

Investigate the meaning of the Pythagorean Theorem through modeling. After comparing the area of the square of each side, individuals cut triangles and squares to facilitate the comparison.

Properly organize parallelograms. Given special parallelograms, the narrator of a short video explains the properties of each. The section of a playlist on geometry uses the properties to classify the special parallelograms.

Why use six corresponding parts when three will suffice? The second of five lessons in the Geometry - Triangle Congruence unit focuses on the SSS and SAS triangle congruence criteria. By watching a video, scholars learn how to identify...

Sometimes one knows more about angles than about sides. Young mathematicians learn about the AAS and ASA triangle congruence criteria by watching an informative video. They use these shortcuts to demonstrate triangle congruence in...

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.

Is the amount of information getting overwhelming for your geometry classes? Use this strategy as a way to organize information. The resource provides a handout of information studied in relation to triangle congruence. It includes a...

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...

Don't believe everything that you hear — make them prove it! The video shows two methods to prove the Triangle Angle Sum Theorem. The following two videos apply the theorem to finding missing angle measures.

Don't be a square! Young mathematicians determine the slope and length of a line segment. They then prove whether four given coordinate points form a square.

Can you prove it? Making assumptions in geometry is commonplace. This resource requires mathematicians to prove the parallel line postulate through constructions. Learners construct parallel lines with a 180-degree rotation and then...

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...

It's time to discover what your classes have learned! The final lesson in the 25-part module is an assessment that covers the Pythagorean Theorem. Application of the theorem includes distance between points, the volume of...

It's not a parallelogram until proven otherwise. Scholars learn about the conditions for a quadrilateral to be a parallelogram. They watch a video to see how to apply the conditions to prove that a given quadrilateral is a parallelogram.

Here's a special lesson about some special parallelograms. The fifth of seven parts in the Geometry - Quadrilaterals and Polygons unit focuses on the conditions for rectangles, rhombuses, and squares. Young mathematicians use these...

Twelfth graders investigate maximum and minimum as it relates to billiard and mini golf. In this calculus activity, 12th graders review how to find the maximum and minimum and write proofs to show how they arrive at their answer. They...

In this stars rise in the east learning exercise, students use geometry to show how the Earth rotates from west to east and why celestial bodies appear to rise in the east and set in the west. Students draw a figure and label given...

Use your pupils' sense of curiosity to explore the Parallelogram Law. Here is an activity that outlines a complete lesson from beginning to end, allowing pupils to follow a conjecture through to the proof stage.

Showing is better than telling in a short demonstration video to find the area of a circle. The silent narrator transforms the circle, made from ball chain, into a triangle you can measure with a ruler, labeling quantities each step of...

In this geometry practice problems worksheet, students write geometric proofs to prove the validity of given circumstances. Students prove parallel lines, perpendicular lines, and similar angles. This four-page worksheet contains eight...

Young scholars examine Triangle Congruency. In this measurement comparison lesson, students use inductive, deductive and analytical thinking skills to prove triangle congruency. Young scholars analyze and record their findings on...