In this geometry instructional activity, 10th graders focus on Euclidean proofs involving triangles and circles.  The eight page instructional activity contains eight proofs.  Solutions are not provided. 

In this identifying similar triangles worksheet, 10th graders solve 5 different proofs related to similar triangles. First, they identify the similar triangles in each figure and explain why they are similar, using the information to...

In this right triangles worksheet, 10th graders solve 6 various problems and figures related to right triangles. First they identify and describe the 3 theorems and 1 postulate stated that prove 2 right triangles congruent if one of them...

In this indirect Euclidean proof worksheet, students write statements supporting the reasons for a given proof. This one-page worksheet contains ten problems.

In this proving figures congruent activity, 10th graders solve and complete 11 different problems. First, they determine the additional information needed to prove the triangles congruent. Then, students determine which postulate, if...

Participants who use this resource will apply the Pythagorean Theorem to show whether or not the shaded triangle inscribed in a rectangle is a right triangle. Once all of the sides on the shaded triangle are found, it is important that...

Learners discuss and review examples of the Pythagorean Theorem using a GSP, Geometer's Sketchpad, activity.

In this right triangles worksheet, 10th graders solve 5 problems that relate to different right triangles. First, they find the values of x and y so that each triangle is congruent to the other. Then, students write a two-column proof...

Geometers explore symmetries of isosceles triangles by using rigid transformations of the plane. They complete four tasks, including congruence proofs, which illustrate the relationship between congruence and rigid transformations. The...

Students study relationships between angles, side lengths, perimeters, areas and volumes of similar objects. In this lesson students also create and critique inductive and deductive arguments concerning congruency, similarity and the...

Having a good working knowledge of math vocabulary is especially important for geometry learners. Here are 119 pages worth of wonderfully constructed definitions, constructions, formulas, properties, theorems, and postulates. This is a...

If both pairs of opposite sides of a quadrilateral are congruent, is the quadrilateral a parallelogram? This task asks learners to determine the answer and to support their answer with a proof. The resource includes a commentary for...

This task asks learners to prove that the segment joining the midpoints of two sides of a parallelogram is both congruent and parallel to an adjacent side of the parallelogram. The activity would be good to use in a discussion about how...

In this circle proofs worksheet, 10th graders complete 4 different problems that include circle proofs. They respond to each of the questions that deal with circle proofs. Then, students read the given information and use the circle...

In this triangle theorems worksheet, students identify the theorem used to prove the specified triangular relationship. Students are shown an illustration of two or more triangles. They identify the postulate that would be used to prove...

What's so special about tangents? Learners first explore how if a circle is tangent to both rays of an angle, then its center is on the angle bisector. They then complete a set of exercises designed to explore further properties and...

Students investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson plan, students discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles are formed by two...

In this properties of geometry worksheet, 10th graders solve and complete 12 different problems that include various theorems. First, they draw a figure that illustrates the SAS inequality property. Then, students prove that two line...

Students investigate the concept of symmetry by using various examples and performing independent practice with scaffolding provided by the teacher. They review reflection symmetry and cover the new rotation symmetry using manipuatives.

Learners investigate the relationship between angles and their sides. In this geometry instructional activity, students prove why SSA does not work as a true angle side relationship theorem.

In this stars rise in the east worksheet, 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 points in...

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...

Young geometers apply their deductive reasoning skills and knowledge of proving triangles congruent in a task that asks them to prove if a point lies on the perpendicular bisector of a segment, then it is equidistant from the endpoints...

Learners cut an index card to create three similar right triangles and explore the congruencies and proportions that exist. They investigate the properties of lines and concepts of congruency, similarity, tangency and symmetry of...