Demonstrates how to make a mobile for hanging above a baby's crib. Explains concepts such as bisecting an angle, determining the perpendicular bisector of a line, constructing a triangle using three known side lengths, determining the center of gravity by constructing medians, determining the inscribed circle of a triangle by constructing angle bisectors, and determining the circumcircle of a triangle by constructing the perpendicular bisectors. Accessibility options on the DVD are: (1) expanded description, (2) English subtitles in a black box, (3) subtitled description. Part of the "Mathemania" series.