CRC cards form the basis of one of the most venerable practical technique for facilitating object-oriented design.
CRC stands for Class, Responsibilities, and Collaborators and each of these are recorded on index cards which are then used to facilitate team-based role-play.
The technique was first introduced by Beck and Cunningham in their paper [1]. It was used as a way to help procedural programmer learn object-oriented design.
Figure 6. The CRC Cards
Beck and Cunningham claim "this approach successful in teaching novice programmer the concept of objects and in introducing experienced programmers to complicated existing designs" [1].
More recently, the technique has become regarded as useful beyond the learning stage because of the subtle way it supports critical characteristics of design[2].
Surveys list CRC cards as a "well tried" technique, and acknowledge applicability of CRC cards beyond simply learning [2].