A logical relationship between activities where one depends on another (for example, Finish-to-Start: one must finish before the next can start).

A significant zero-duration point in the project, such as 'Contract signed' or 'Go-live', used as a key control and reporting point.

The longest path through the network of activities, which determines the shortest possible project duration. Activities on it are critical.

The amount of time an activity can be delayed without delaying the project finish date. Critical activities have zero total float.

A significant event or point in a project with zero duration, used to mark progress and control, often shown as a diamond on a Gantt chart.

A logical link between activities, showing which must be completed or started before others can begin.

A bar chart representation of a schedule with time on the horizontal axis and activities as horizontal bars, showing durations, overlaps and often dependencies.

Putting Time in Order: Scheduling, Dependencies and Critical Path Basics — APM PFQ Essentials with Citivirtual: Fast-Track to Project Fundamentals

From Task List to Schedule: The Big Picture

From List to Schedule

You already know what the project must deliver and have basic estimates. Now you must answer: When will this be done? This means turning a list of activities into a realistic schedule.

Core Scheduling Steps

At PFQ depth, focus on logic, not software. The basic steps are: list activities, find dependencies, estimate durations, place them on a timeline, identify milestones and the critical path, then use the schedule to track progress.

Two Common Views

You will usually see schedules shown as: 1) Bar charts (Gantt) with time along the top and bars for activities; 2) Network diagrams with activities in boxes and arrows for dependencies.

What You Will Be Able To Do

By the end you should be able to build a simple schedule from a task list, explain dependencies, milestones and float, and interpret a basic bar chart or network diagram for key control points.

Step 1: Define Activities (Activity-Based Planning)

What Is an Activity?

An activity is a piece of work with a clear start and finish, a responsible owner, and an estimated duration. Activities come from your scope and work breakdown structure.

Guidelines for Activities

Make activities specific, manageable (often 1–10 working days), described as work not people, and include key checks such as reviews and approvals as activities too.

Website Example Activities

For a student society website, activities might be: confirm requirements, choose domain, set up hosting, design homepage, build pages, test site, committee review, and launch and announce.

Why This Matters

In scheduling tools each activity is a line in the plan. A realistic schedule depends on having a sensible, well-defined list of activities first.

Activity List Practice

Imagine you are organising a one-day student conference.

Write down 5–8 activities (not in order) that would need to happen between now and the conference day.

Use these prompts:

Start with scope: what must exist on the day? (venue, speakers, marketing, catering)
Turn each into work: what has to be done to make that real?

Example of one good activity: `Confirm booking with venue and pay deposit`.

Now check each of your activities:

Does it have a clear start and finish?
Could you estimate its duration in days?
Does it describe work, not a person?

If any fail these checks, rewrite them to be more specific.

You will use this same list again in later steps, so keep it handy.

Step 2: Dependencies – What Must Happen First?

What Is a Dependency?

A dependency is a logical relationship between activities. It tells you which activities rely on others finishing or starting before they can begin.

Common Dependency Types

The main type is Finish-to-Start (FS): B cannot start until A finishes. Others exist (Start-to-Start, Finish-to-Finish, Start-to-Finish) but PFQ focuses mainly on FS.

Website Dependency Examples

You must set up hosting before you test the site, design the homepage before building content pages, and test the website before the committee review and approval.

Building the Logic

Write each activity on a note and ask: "What must be completed before this can start?" Draw arrows from predecessors to successors. This becomes the basis of your network diagram.

Map Dependencies for Your Conference

Return to your student conference activity list.

Write your activities as a numbered list.
For each activity, answer: "Which activities must finish before this can start?"
Next to each activity, note its predecessors (if any) by number.

Example pattern:

Confirm venue booking (no predecessors)
Invite speakers (predecessor: 1)
Open registration (predecessor: 2)
Confirm catering numbers (predecessor: 3)

Now imagine this as a network diagram:

Each activity is a box with its number.
Draw arrows from predecessor numbers to successor numbers.

Reflection questions:

Which activities can start right away (no predecessors)?
Which activities are bottlenecks (many others depend on them)?

Write down one activity that looks particularly critical and keep it in mind for the critical path step.

Step 3: Durations, Simple Network and Milestones

Add Durations

Next, estimate how long each activity will take in working days. For the website, activities like "Confirm requirements" might be 2 days, "Design homepage" 4 days, and "Build content pages" 5 days.

Visual Network (Text Description)

Imagine each activity as a rectangle with its number and duration, joined by arrows. For example: 1 → 2 → 4, and 1 → 3 → 4, then 4 → 5 → 6 → 7 → 8, flowing left to right.

What Is a Milestone?

A milestone is a significant point in the project with zero duration, such as "Design signed off" or "Website ready for launch". It marks key control points.

Using Milestones

In bar charts milestones are often diamonds; in networks they may be small circles. They let sponsors track progress at key points without reading every activity.

Step 4: Forward Pass, Critical Path and Float (Conceptual)

Critical Path Concept

The critical path is the longest path through the network, considering durations and dependencies. It sets the earliest possible completion date for the whole project.

What Is Float?

Float (slack) is how long an activity can be delayed without delaying the project finish. Activities on the critical path have zero total float and are called critical.

Thinking Forwards

Conceptually, you "walk" from start to finish adding durations along each dependency chain. The chain with the largest total time is the critical path and gives the project duration.

Website Example Paths

For the website, there are two main paths: 1–2–4–5–6–7–8 and 1–3–4–5–6–7–8. Whichever totals longer is the critical path; activities on the shorter path may have float.

Critical Path Thought Exercise

Imagine this simple project with durations in days:

A: 2 days (start activity)
B: 3 days, depends on A
C: 4 days, depends on A
D: 2 days, depends on B and C

List the possible paths from start to finish:

Path 1: A → B → D
Path 2: A → C → D

Add up durations for each path.

Decide:

Which path is the critical path?
Which activity (B or C) has float, and why?

Hint: Both paths share A and D. Compare the B vs C branches.

Write your reasoning in full sentences, as if explaining to a non-technical sponsor. Focus on the idea of longest path and float, not on formal formulas.

Check Understanding: Dependencies and Critical Path

Answer this PFQ-style question.

Which statement best describes a critical activity in a simple project network?

It is the activity that uses the most resources.
It is any activity that has zero float and lies on the longest path through the network.
It is the first activity to start in the project.
It is any activity that finishes with a milestone.

Show Answer

Answer: B) It is any activity that has zero float and lies on the longest path through the network.

A critical activity is one with zero total float that lies on the critical path, the longest path through the network. Delaying a critical activity will delay the project finish. Resource use, start order, or being linked to a milestone do not by themselves make an activity critical.

Step 5: Reading a Bar Chart (Gantt) for Control Points

What Is a Gantt Chart?

A Gantt chart is a bar chart with time along the top. Each activity is a horizontal bar showing when it starts and ends. Dependencies are often arrows; milestones are diamonds.

Website Gantt Example

For the website, you might see "Confirm requirements" as a 2-day bar, then "Register domain" as a 1-day bar, later "Test website" as a 3-day bar linked from "Build content pages".

Reading the Chart

To interpret: find total project duration, identify milestones and ends of critical activities, check which activities overlap, and compare actual progress to the planned bars.

Spotting Critical Chains

Even without calculations, you can often see a chain of back-to-back bars from start to finish. This unbroken chain usually represents the critical path.

Check Understanding: Milestones and Float

Another quick question to consolidate your learning.

Which of the following is the best description of a project milestone?

A task that must be completed by the project manager personally.
A significant zero-duration point used to mark progress, such as 'Design approved'.
Any activity that has float greater than zero.
The activity with the longest duration in the schedule.