Project Planning and Scheduling
Planning decides what work, in what order, with what resources; scheduling places it on a timeline. Know the work breakdown structure (WBS), activity sequencing, and dependencies (finish-to-start is most common). Understand the critical path method (CPM): the longest path through the network sets the project duration, and activities on it have zero float. Total float is the time an activity can slip without delaying the project; free float is the slip allowed without delaying the next activity.
Understand bar charts (Gantt) for communication and network diagrams for logic. Know how to calculate early start/finish and late start/finish by forward and backward pass. Resource levelling smooths peaks within float; resource smoothing may extend duration. Crashing adds resources to shorten the critical path, usually at extra cost.
Traps: assuming the most expensive or longest activity is critical-only the longest path is; confusing float with slack in a different chain; and forgetting that shortening a non-critical activity does not shorten the project. Also watch for multiple critical paths and for lag/lead in dependencies.
Rule of thumb: the critical path is the chain with zero total float; to shorten the project you must shorten a critical activity.
Worked example: Path A–B–C = 5+7+4 = 16 days; path A–D = 5+6 = 11 days. Duration is 16 days; A, B, C are critical. D has 5 days total float. Adding a day to D changes nothing; adding a day to B extends the project to 17 days.