This paper addresses the concept of geological time as used by students who face tasks that demand three types of skills: to locate events in time, to order them according to time calendar, and to manage time intervals. The empirical study consisted of asking high school students as well as technical school students to carry out tasks that…

Describes various ways a user can control computer program activity using different menu constructions. Advantages, disadvantages and program design principles for menu design are discussed. A listing for a menu demonstration program is included. (BC)

Presented is an accounting of known numbers of major categories of life, from viruses to mammals. The construction of the census is described. Included are living and nonliving species and genera. (CW)