Are two angles enough? Given two triangles, the class determines through the definition of similarity and transformations whether the two triangles are similar. Provided with pairs of triangles and measurements, small groups find out...

Enjoy this nicely organized worksheet that puts together multiple problems regarding trapezoid proofs. The resource can be used as a guide that begins with proving properties and ends with solving for measures of line segments.

Stuck with triangle proofs? Take a 180° and provide learners with a guided worksheet that tests their knowledge with triangle inequalities. The questions require different types of proofs that range in levels of difficulty. 

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. 

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...

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...

Lead by example. Pupils use software to investigate given measures of sides and angles to determine whether they create congruent triangles. Using the discovered triangle congruences, learners put together proofs.

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.

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...

Cut straight to the proof. Given cutouts of different quadrilaterals, pupils draw diagonals. Learners cut up the figures along the diagonals to see whether they bisect each other. Scholars develop a geometric proof for the property they...

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.

What does every circle have in common? Learners explore this question as they prove all circles are similar. A series of activities leads them to this conclusion by identifying transformations.

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...

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...

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...

What do congruent triangles have to do with diagonals of a rhombus? Given a rhombus, pupils develop a proof showing that a diagonal bisects opposite angles. The learners use what they know about congruent triangles to create the...

Verify a figure by using coordinates. Pupils calculate the coordinates of the midpoints of the sides of a quadrilateral. They then use the coordinates to show the resulting figure is a parallelogram. 

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...

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...

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.

What is so special about right triangle congruence? Pupils use what they know about transformations and right triangles to develop a proof of hypotenuse-leg congruence. The proof provides the given of two angles that measure 90 degrees...

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...

Are congruent corresponding sides of two triangles enough to show congruence? The short assessment provides two triangles with the information that the three sets of corresponding sides are congruent. Pupils develop a proof showing that...