Use the alphabet as a tool for teaching your class about geometric figures. Break apart capital letters into line segments and arcs. Classify angles as right, acute, or obtuse. Identify parallel and perpendicular lines. An excellent...

One of the hardest skills for many young geometers to grasp is to move beyond just declaring obvious things true, and really returning to fundamental principles for proof. This brief exercise stretches those proving muscles as the...

Your Geometry learners will collaboratively prove that the tangent line of a circle is perpendicular to the radius of the circle. A deliberately sparse introduction allows for a variety of approaches to find a solution. 

This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...

Geometry meets earth science as high schoolers investigate the cause and features of the four seasons. The effects of Earth's axis tilt features prominently, along with both the rotation of the earth about the axis and its orbit...

This is an interesting geometry problem. Given the figure, find the area of a triangle that is created by the intersecting lines. The solution requires one to use what he/she knows about coordinate geometry, as well as triangle...

Inscribing a square in a circle brings up a number of interesting geometry topics including triangle congruence and how to prove a quadrilateral is a square. This activity is followed up by finding the area of the square and determining...

Triangle centers and the segments that create them easily become an exercise in memorization, without the help of engaging applications like this lesson. Here the class investigates the measure of center that is equidistant to the three...

Geometry gets an engineering treatment in an exercise involving a belt wrapped around two wheels of different dimensions. Along with the wheels, this belt problem connects concepts of right triangles, tangent lines, arc length, and...

Need an activity for teaching the Pythagorean Theorem? Geometry juniors apply the Pythagorean theorem to two triangles to determine a final calculation. 

In this geometry worksheet, students create a map that uses various geometrical concepts. The final project is the creation of a "geometrical town." Rubric for grading is included.

Your learners find and construct the line of reflection between a triangle's pre-image and its reflection image in this short activity.

Your geometry learners will discover and show the construction of the circumcenter of a triangle. Guided by the steps in the activity, they construct perpendicular bisectors of each side that have a point of concurrency called the...

Your geometry learners are guided by questions that help them use the language of reflections to explain the Side-Angle-Side congruence between two triangles in this collaborative task. Given a sample solution, declaring the...

An upper-level treatment of what is often presented as a basic concept (the right angle of an inscribed circle on the diameter), this activity really elevates the mathematical thought of the learner! Expected to develop formulas...

Combine algebraic and geometric strategies to find solutions. The task asks learners to find the coordinates of a third vertex of a triangle to create a triangle with a specific area. The project is a set of seven problems that...

This activity will help students understand the relationship between the slopes of parallel and perpendicular lines.

This activity has students discover the relationship between parallel and perpendicular lines and their slopes. After constructing these objects using CABRI Geometry II for the TI-89, slopes are measured. [Requires Adobe Reader.]

In this activity, students use the Cabri software to mark points, draw lines, construct parallel and perpendicular lines, angles, bisectors, and triangles. They learn how to use the tool to measure angles.

Learners explore the definitions and properties of the perpendicular bisector. The interactive activity includes an applet to explore the properties of the perpendicular bisector.

Practice using your graphing calculator for geometry problems, including the use of the Pythagorean Theorem and the distance formula. If you get stumped or if you would like to check your work, then select the View Solution button, which...

In this activity students explore the tangent ratio. Students construct a right triangle using perpendicular lines, and a line that forms the hypotenuse of the triangle. When students construct the hypotenuse line it is very important...

This step-by-step method teaches students to construct a perpendicular to a line through a point on--or off--the initial line using compass and straight edge.

Find resources for class instruction on concurrence: a lesson on concurrence of medians, altitudes, angle bisectors, and perpendicular bisectors complete with definitions and example diagrams; a six-question practice quiz; and...