Program Evaluation and Review Technique (PERT) and Critical Path Method (CPM) help managers to plan the timing of projects involving sequential activities. PERT/CPM charts identify the time required to complete the activities in a project, and the order of the steps. Each activity is assigned an earliest and latest start time and end time. Activities with no slack time are said to lie along the critical path–the path that must stay on time for the project to remain on schedule.