Details a lesson that utilizes trigonometric identities to determine the optimal angle between the atoms of covalent bonds. Generates a proof of the optimal angle for a molecule with four identical atoms bonded to a central atom that has a complete valence shell. (DDR)

Describes a kangaroo simulation which can be adapted for use with radio tracking activities for other animals. Outlines procedures and information to help implement the activity. Provides a map of Australia, calculations, and sample kangaroo movement data. (RT)