Abstract
′Homines dum docent discunt′ means: ′People learn while they teach.′ (Or, alternatively, ′Men learn while they teach.′) This is a quote from the 7th letter of Seneca to Lucilius. Todays, the nation is facing an educational crisis, and truely academic standards are declining. The majority of people discuss decline of ability in university students. Decline of ability can be explained in terms of numeros points of views. However, we, university educators, must get the knack of teaching and teach the joy of learning. In this paper, mysterious behaviour of moving curves are introduced from a view point of differential geometry and kinematics, and the involute curve of gear tooth are shown to elegantly be obtained.
