Meet the lab

The WBS Scheduler looks and behaves like a desktop scheduling tool, deliberately. If you move on to P6 or Microsoft Project, the layout will feel familiar.

The screen

• Menu bar and toolbar. Schedule (F9), add and delete activities, step through the CPM calculation, and switch views on and off.
• Activity grid (left). One row per activity: ID, name, duration, start, finish, total float (TF), free float (FF) and predecessors. Click a cell to edit it.
• Gantt chart (right). The same activities on a timeline. Weeks run across the top.
• Details pane (bottom). Three tabs for the selected activity: General (dates and float in plain words), Relationships (add, change or delete links) and CPM math (the calculation behind its dates).
• Lab tasks (bottom right). What to do in this lab. Tasks tick themselves when you’ve done them.
• Status bar. Project start and finish, the number of critical activities, open ends, and whether the schedule is up to date.

Reading the Gantt chart

You see	It means
Green bar	An activity with float
Red bar	A critical activity: no float
Diamond	A milestone: zero duration, marks a moment
Grey line after a bar	Total float: how far the activity can slip before the project finish moves
Solid arrow	A driving relationship: it sets the successor’s date
Dashed arrow	A non-driving relationship: there is slack between the two activities

Editing

Click a name or duration and type. For predecessors, type activity IDs separated by commas. A plain ID means finish-to-start; add the type and a lag when you need them:

Type this	Meaning
A1010	Finish-to-start from A1010
A1010 SS+2	Start-to-start from A1010, 2 days lag
A1020 FF-1	Finish-to-finish from A1020, 1 day lead

The Relationships tab does the same with menus, if you prefer.

Scheduling

Most desktop schedulers don’t recalculate after every keystroke. P6 waits until you press F9. This tour works the same way: change something and the status bar says Changes not scheduled. Press F9 and the dates update. In later labs auto-schedule is on, so the dates move as you type; you can switch it in the Schedule menu.

The office move

The project below plans a new floor layout, orders furniture, runs network cabling, paints, installs the furniture and moves in. As delivered it finishes on Day 17, Tuesday 24 November. Two paths lead to Install furniture: furniture delivery (15 days of work after the start) and cabling plus painting (12 days). The longer one sets the date, which is why cabling shows 3 days of float.

In the lab, make the furniture supplier slower and watch Move-in slip to Day 19. Then make the cabling crew slower and see what happens to Move-in, and why.