Curated OER
Ellipses And Kepler's First Law
High schoolers explain that planets actually orbit the center of gravity of the solar system, and that distant planets may be detected by motions of their central star around the centers of gravity of their planetary systems.
Curated OER
Investigating the Idea of Tan
Fifth graders use tan to solve problems involving right-angled triangles. They solve equations of the form tan(8) =a, for a between 180 degrees and 360 degrees. They state the value of tan (8) in special cases.