Curated OER
Similarity and Congruence
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...
Curated OER
Exterior and Interior Angles of Triangles
Tenth graders explore the exterior and interior angles of triangles. They use a theorem in order to prove a theorem about all polygons. Students use the theorem and its applications to find the angles of different types of triangles.
Curated OER
Introducing Trig
Fifth graders explore the importance of triangles in the real world. They find the unknown side of a right triangle using a scale drawing. Students use Pythagoras' Theorem and other appropriate ratios.
Curated OER
Math: Seifert Surface
Students use wire to make knots and submerse them in pans of detergent to observe how the soap film clings to the wire. They discover this film is called the Seifert Surface. After drawing pictures of the surface, they discuss what...
Curated OER
Math: Tangents
Students discover how to recognize tangents and how to use their properties. They investigate and use the properties of angles, arcs, chords, tangents, and secants. Students use two tangents and the properties of similar triangles to...