A connected introduction of angle measure and the sine function entails quantitative reasoning.
Kevin C. Moore and Kevin R. LaForest
Zhonghong Jiang and George E. O'Brien
Using technology to explore the Three Altitudes of a Triangle problem, students devise many proofs for their conjectures.
This is a description of a collaborative investigation by mathematics teachers into the numbers of dimensional boundaries for n > 2. Functions are fit to the patterns observed, and a relationship to Pascal's triangle is noted.
Samuel Obara and Zhonghong Jiang
Applying Zometool, vZome software, and The Geometer's Sketchpad to tetrahedrons nested in cubes enhances students' spatial visualization skills.