This is the fifth in a series of publications to help teachers use a mathematics laboratory approach in the elementary school. It provides 64 activities, developed by teachers and field-tested in classrooms. It is designed to be used with any basic mathematics program, as a stimulant to encourage teachers to use their imagination to develop further activities. In developing a set of task cards, the teacher should adjust vocabulary used in the publication and choose concrete materials in terms of knowledge of the particular children and the type and amount of manipulative materials available. For each activity, materials needed, purpose, procedures and suggestions are given. (MNS)