Students discover three lettered postulates that prove triangles congruent.

High schoolers view examples of a ray, opposite rays, collinear rays, angles, and straight angles. They discuss and demonstrate how to use a protractor and complete worksheet problems on rays and angles.

Students explore the concept of similarity and congruence. In this similarity and congruence instructional activity, students identify and verify whether or not two figures are similar, congruent, or neither. Students use postulates and...

Students determine that two figures are similar or congruent by investigating figures that are similar and figures that are congruent. They prove that two figures are similar or congruent by using definitions, postulates, and theorems.

Students discuss the sum of central angles and use string to create them on circles. They find the measure and length of both minor and major arcs. Students give examples of concentric, similar, and congruent circles and congruent arcs.

Students view a PowerPoint for a warm-up lesson. They practice measuring around the classroom, measuring such things as the length and width of a desk, pencil, door, and book. Students use a website to practice measuring angles.

Students differentiate between similarity and congruence using polygons. For this geometry lesson, students label triangles based on their properties. They find missing sides and angles using the interior sum theorem.

High schoolers explore the concept of similarity and congruence. For this similarity and congruence lesson, students cut out strips of paper and form a triangle. High schoolers try to prove that their triangles are congruent using the...