Students draw triangles and explore the classification of each using the measures of interior angles and lengths of sides. They investigate the sum of the interior angles of various triangles and conjecture and prove the theorem: The...

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 instructional...

Tenth graders investigate the theorems of angles and lines to prove triagle sum theorem. In this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two...

Students calculate the sum of the angles of a polygon. In this geometry lesson, students use the interior angle formula of polygon based on the number of sides of the polygon. They identify the missing angle using algebra.

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

Junior geometers discover that polygons can be decomposed into triangles and that the number of triangles can be determined by a rule. Note that the Geometer’s Sketchpad® software is required to carry out all components of this...

Properties about triangles are explored in this lesson. Geometers make conjectures about the length of a triangle's sides, the length of the angles in relation to the length of the sides, and the measure of the exterior angles of a...

Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson, 10th graders 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...

Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson plan, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles are formed...

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

Students identify diagrams of quadrilaterals and circles by different names and classify the figures. They name the areas for each diagram and practice solving the formulas for each.

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...

Practice evaluating polynomial expressions at the same time you find Pythagorean Triples. Look for patterns and find examples when the "formula" does and doesn't work. Finally, verify the formula by proving the identity true.

Students examine a math worksheet and determine how to divide a single triangle into four of equal area. Using geometric principles, they sketch two additional ways to divide into into four equal triangles. To conclude, students...

Oh that Pythagorean Theorem is so useful. Learners engage in a 45 minute learning activity that requires them to solve for missing angles and sides of a right triangle. They'll use the Pythagorean Theorem to find the rations of sides and...

Students create both a visual and formal proof of the Pythagorean theorem, as well as view four additional geometric demonstrations of the theorem. They construct a square and conjecture the following theorem: The sum of the areas of...

Students discover the sum of the interior and exterior angles of several polygons. In this Geometers sketchpad lesson, students work in groups to find the stated measurements of triangles, quadrilaterals, pentagons and hexagons. Students...

High schoolers differentiate between similarity and congruence using polygons. In this geometry activity, students label triangles based on their properties. They find missing sides and angles using the interior sum theorem.

Students construct a convincing argument that the same amount of fabric is needed for each color of quilt being made in a specific design. They justify the relationship between vertical angles and the sum of the interior angles. Students

High schoolers explore the concept of polygon properties. In this polygon properties lesson, students draw polygons with different numbers of sides such as pentagons, octagons, hexagons, etc. High schoolers identify different geometric...