How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Learners are asked to divide the...

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,...

Assist your class with each angle of geometry as they use exterior angles to form linear pairs with adjacent interior angles. They cover multiple vocabulary terms and work practice problems, complete with justifications, before...

This a fun problem for young geometers to play with while gaining important insight into deductive reasoning. Some will find the answers very quickly, others might take a less direct path, but all will use their knowledge of the sum of...

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...

High schoolers investigate the sum of the measures of the angles of a triangle. They draw a triangle and measure the interior angles. Using Cabri Jr., learners find the sum of the measures of the interior angles. The lesson provides an...

Angles and triangles: they're all connected. Uncover the connections between angles in triangles. Scholars learn how to find both exterior and interior angle measures in triangles. The lesson emphasizes the vocabulary related to these...

Students draw a chart (included in the lesson) to use with their investigation. They review terminology of triangles and receive toothpicks to use in the lesson. Beginning with three toothpicks, students form a triangle. They complete...

Teach your class how to solve problems using the triangle sum theorem. In this geometry lesson, students identify the missing angles in a triangle using the sum theorem. They graph triangles on the TI and moves the sides around to create...

Try to find the triangles in various polygons. An investigation has learners develop a formula for the sum of the measures of the interior angles of a polygon. They use manipulatives to partition each polygon into triangles, then...

Lead the class in a Greek history lesson with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete...

Learners explore the measures of the angles of a triangle in this geometry lesson. They use Cabri Jr. to investigate the sum of the measures of the interior angles of a triangle, and examine the relationships between the interior and...

Can your classes apply the knowledge they have learned? Use this performance task to find out! Individuals use transformations to explain congruence and angle relationships within parallel lines to find missing values. They show what...

Young scholars estimate and measure triangles. In this geometry instructional activity, students identify the relationship between three sides and a triangle. They use the inequality theorem to decide if a triangle will be formed or not.

Students identify the interior and exterior measures of polygons. For this geometry lesson, students identify the formula for interior angles of polygons. They differentiate between triangular and polygons angles.

Students investigate the interior angles of a triangle. In this geometry lesson, students create the formula to calculate the angles inside a triangle. They observe the total sum of a triangles angle on the navigator.

High schoolers investigate properties of the four centers of a triangle and explore a special property of the circumcenter and orthocenter of a triangle. This lesson requires the use of Cabri, Jr.

Sixth graders discover the patterns of sums of polygon angles. In this math lesson, 6th graders study the properties of geometric shapes to solve problems as they participate in hands-on activities.

Students add up the different angles using the angle addition postulate. In this geometry lesson, students differentiate between interior and exterior angles. They calculate the different angles for triangles and use proof to show their...

Students find triangular angles using the angle theorem. In this geometry lesson, students describe labeled triangles, use the pythagorean theorem, and rewrite information about triangles in standard form.

Students use the inequality theorem to solve triangles and their properties. In this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...

What does it mean for a quadrilateral to be cyclic? Mathematicians first learn what it means for a quadrilateral to be cyclic. They then investigate angle measures and area in such a quadrilateral.

Students use Geometer's Sketchpad to draw triangles and explore the classificaiton of each using the mearsures of interior angles and the lengths of the sides.

In this interactive instructional activity, students review attributes of equilateral polygons. They are introduced to the concept of a tessellation. Using protractors and pre-cut shapes, students arrange a variety of tiles to create...