Methods of tryout and revision in development of instructional materials are identified and explained. Both "front-end" and "rear-end" analyses are included. Ways of anticipating potential student failures--identified as test failures, program task failures and learning failures--are discussed, with specific areas of possible breakdown illustrated. Likewise, the characteristics of inadequately designed individual program tasks, transitions between tasks, and cumulative learning experiences are delineated. Tools used in post-development diagnosis are described, and illustrations are given of diagnostic results which can be linked to specific student learning failures and specific program design failures. Revision techniques are listed for each variety of failure, along with priorities for implementation which can make the process efficient as well as effective. (SK)