In contrast to the student teams used for larger and longer group projects, in-class groups are often ephemeral, lasting for only a few minutes or until the end of the period. Because of this, little effort is put into forming these groups, usually letting the students self-select their teams. This paper argues that greater student interaction and learning can take place by using instructor-selected teams. Two group formation techniques for in-class group work, the latent jigsaw method and grouping students by Felder-Silverman learning styles, are presented. Observations from a classroom deployment of these techniques are also described. Categories and Subject Descriptors K.3.1 [Computers and Education]: Computer Uses in Education—Collaborative learning General Terms Human Factors, Performance Keywords collaborative learning, active learning, learning styles