Scope statements and work breakdown structures

A college’s first plan for its tech fest listed “book the venue” and “do publicity”, counted the sponsor stalls twice and had no branch at all for running the project itself. A checker run on it below finds 6 problems; the corrected structure holds the fest’s 232 hours of work, each hour exactly once.

You will write a scope statement that says what is delivered and what is not, break it down into a work breakdown structure, describe its work packages in a dictionary, and decide when a Product Backlog should hold the scope instead.

A scope statement says what is delivered, how it is accepted and what is left out

Before anyone breaks the work down, the project writes down its scope. A scope statementscope statement: A written description of a project's deliverables, how each will be accepted, and what is explicitly out of scope. lists the deliverables, says how each one will be accepted, and names what the project will not do. PMI’s 2026 outline puts the three steps of scope in order: define scope, obtain stakeholder agreement on it, and break it down. Here is the fest’s scope statement:

Out of scope: food stalls, which the canteen runs; accommodation for visiting students; a hackathon, which was proposed and turned down; live streaming.

Every exclusion here was asked for by someone. Writing it down means that when it is asked for again, the answer is already agreed, and adding it becomes a decision instead of a favour.

A WBS holds all the work in deliverables, each piece exactly once

A work breakdown structurework breakdown structure: A tree that divides a project's whole scope into deliverables and smaller deliverables, named as nouns, in which every element's children hold all of its work exactly once. divides the whole scope into deliverables, and those into smaller ones, until each piece is small enough to estimate and give to an owner. NASA’s WBS handbook calls it a product-oriented family tree of every deliverable the project needs, and adds that work not in the WBS is not part of the project. Two rules follow, and planners usually call the first one the 100 % rule:

• the children of every element hold all of its work and nothing else, so the hours at each level add up exactly;
• elements are deliverables named as nouns, because, as GAO’s schedule guide puts it, the WBS says what is required and the schedule says how it will be produced.

NASA’s handbook also asks for the work that is not a product, such as project management, to have its own elements. The program below checks the fest’s first draft against these rules and prints the corrected WBS with its codes and hours:

"""Checks two work breakdown structures for an invented college tech fest, then prints the corrected one with its
codes and hours rolled up.

A WBS element is a deliverable, named as a noun; the leaves are work packages with an estimate in hours. The checks:
no element starts with a verb (activities belong to the schedule), no element appears twice (the same work counted in
two places), and every deliverable of the brief has its own branch. A parent's hours are the sum of its children's, so
the top holds all the work exactly once.
"""

BRIEF = ["Venue", "Sponsorship", "Events", "Registrations", "Publicity", "Safety", "Closure", "Project management"]
VERBS = {"book", "do", "make", "arrange", "run", "create", "organise", "prepare", "write", "hire", "buy", "print"}

DRAFT = ("College tech fest", [
    ("Book the venue", [("Auditorium booking", 6), ("Sound and lights", 10)]),
    ("Sponsorship", [("Sponsor packages", 12), ("Sponsor stalls", 8)]),
    ("Events", [("Coding contest", 40), ("Robotics challenge", 36), ("Talks", 16)]),
    ("Registrations", [("Online form", 10), ("Registration desk", 12)]),
    ("Do publicity", [("Posters", 8), ("Social media campaign", 14), ("Sponsor stalls", 8)]),
    ("Safety", [("First aid post", 6), ("Crowd plan", 10)]),
    ("Closure", [("Accounts and refunds", 8), ("Closure report", 6)]),
])

FIXED = ("College tech fest", [
    ("Venue", [("Auditorium booking", 6), ("Sound and lights", 10), ("Seating and stage", 8)]),
    ("Sponsorship", [("Sponsor packages", 12), ("Sponsor stalls", 8)]),
    ("Events", [("Coding contest", 40), ("Robotics challenge", 36), ("Talks", 16)]),
    ("Registrations", [("Online form", 10), ("Registration desk", 12)]),
    ("Publicity", [("Posters", 8), ("Social media campaign", 14)]),
    ("Safety", [("First aid post", 6), ("Crowd plan", 10)]),
    ("Closure", [("Accounts and refunds", 8), ("Closure report", 6)]),
    ("Project management", [("Plan and budget", 12), ("Weekly status meetings", 10)]),
])


def names(element):
    name, content = element
    yield name
    if isinstance(content, list):
        for child in content:
            yield from names(child)


def problems(wbs):
    found = []
    all_names = list(names(wbs))
    for name in all_names:
        if name.split()[0].lower() in VERBS:
            found.append(f'"{name}" starts with a verb: name the deliverable, not the activity')
    for name in sorted({n for n in all_names if all_names.count(n) > 1}):
        found.append(f'"{name}" appears {all_names.count(name)} times: its work is counted twice')
    branches = [child[0] for child in wbs[1]]
    for deliverable in BRIEF:
        if deliverable not in branches:
            found.append(f'no branch for "{deliverable}"')
    return found


def hours(element):
    content = element[1]
    return content if isinstance(content, int) else sum(hours(child) for child in content)


def show(element, code="1", depth=0):
    print(f"{'  ' * depth}{code:<7}{element[0]:<26}{hours(element):>4} h")
    if isinstance(element[1], list):
        for i, child in enumerate(element[1], start=1):
            show(child, f"{code}.{i}", depth + 1)


for title, wbs in (("Draft", DRAFT), ("Corrected", FIXED)):
    found = problems(wbs)
    print(f"{title}: {len(found)} problems")
    for line in found:
        print(f"  - {line}")
print()
show(FIXED)

Draft: 6 problems
  - "Book the venue" starts with a verb: name the deliverable, not the activity
  - "Do publicity" starts with a verb: name the deliverable, not the activity
  - "Sponsor stalls" appears 2 times: its work is counted twice
  - no branch for "Venue"
  - no branch for "Publicity"
  - no branch for "Project management"
Corrected: 0 problems

1      College tech fest          232 h
  1.1    Venue                       24 h
    1.1.1  Auditorium booking           6 h
    1.1.2  Sound and lights            10 h
    1.1.3  Seating and stage            8 h
  1.2    Sponsorship                 20 h
    1.2.1  Sponsor packages            12 h
    1.2.2  Sponsor stalls               8 h
  1.3    Events                      92 h
    1.3.1  Coding contest              40 h
    1.3.2  Robotics challenge          36 h
    1.3.3  Talks                       16 h
  1.4    Registrations               22 h
    1.4.1  Online form                 10 h
    1.4.2  Registration desk           12 h
  1.5    Publicity                   22 h
    1.5.1  Posters                      8 h
    1.5.2  Social media campaign       14 h
  1.6    Safety                      16 h
    1.6.1  First aid post               6 h
    1.6.2  Crowd plan                  10 h
  1.7    Closure                     14 h
    1.7.1  Accounts and refunds         8 h
    1.7.2  Closure report               6 h
  1.8    Project management          22 h
    1.8.1  Plan and budget             12 h
    1.8.2  Weekly status meetings      10 h

The draft fails 6 checks: two branches named as activities, which also hides the venue and publicity deliverables of the brief, sponsor stalls counted under two branches, and no branch for project management. In the corrected WBS every parent’s hours are the sum of its children’s: 92 hours of events are 40 + 36 + 16, and the eight branches give 232. Follow one branch down until the WBS stops and the schedule begins:

Work packages carry the estimate, the owner and a dictionary entry

The lowest elements of a WBS are work packageswork package: A lowest element of a work breakdown structure, small enough to estimate, give to one owner and check as complete., where estimates and owners are given. How small they should be is a matter of judgement: GAO’s guide says work packages are ideally about 4 to 6 weeks long, and many teams use a rule of thumb of 8 to 80 hours of effort. A rule of thumb is not a standard; what matters is that the package can be estimated and its completion checked.

Each work package gets an entry in the WBS dictionaryWBS dictionary: The companion document of a work breakdown structure that describes each element: what it contains and does not, how it is accepted, its owner, estimate and dependencies., the companion document that describes what the element contains. NASA’s handbook says the dictionary exists to make sure all the scope is identified and to remove duplication and overlap between assignments. Two entries of the fest’s dictionary:

The last row matters most. “Not included” draws the line between neighbouring packages, so that first aid is planned once, under 1.6.1, and not again under the crowd plan.

A Product Backlog grows as the team learns; a WBS is fixed up front

A WBS fixes the scope early and protects it with change control, which suits work whose deliverables are known or promised. Adaptive work holds its scope differently. The 2020 Scrum Guide calls the Product BacklogProduct Backlog: In Scrum, the emergent, ordered list of what is needed to improve the product; items are added, split and reordered as the team learns. “an emergent, ordered list of what is needed to improve the product”: items are added, split and reordered as the team learns, and the most valuable come first.

Many projects use both. A city’s ticketing app might hold the contract’s fixed deliverables, the payment integration, the accessibility audit and the data migration, in a WBS, and the app’s features in a backlog under one branch of it. Try the figure on a project you know; three answers decide which way of holding its scope still fits:

Fixed commitments call for a WBS, features still being discovered call for a backlog, and work with both gets both, with the backlog living under the WBS branch that holds the product.

Practise: scopes, structures and packages

The questions bring other projects to break down: a wedding, an office move, a website and a city’s app. Choose an answer, see why it is right or what it misses, and the parts you find hardest come back:

Interview questions

Warm-up (fresher to 2–5 years): what is the 100 % rule of a work breakdown structure?

The 100 % rule says that the children of every element of a work breakdown structure contain all of that element’s work and nothing more. Added up level by level, the work of the lowest elements gives each parent’s total exactly, and the top element holds all of the project’s work. Two faults break it: missing work, such as a project with no branch for project management itself, and work counted twice, such as sponsor stalls listed under both sponsorship and publicity. Naming elements as deliverables rather than activities helps, because two branches can easily describe the same activity in different words.

Two harder questions follow, about coaching someone whose WBS is full of activities and about a client who wants a fixed price and changing features. Decide what you would say before you open each first step:

Key takeaways

• A scope statement lists the deliverables, how each one will be accepted and what is explicitly out, so that adding an excluded item later is a visible decision.
• A work breakdown structure divides the scope into deliverables named as nouns, and the children of every element hold all of its work exactly once, so the hours add up at every level.
• Work packages are the lowest elements, sized to be estimated and owned, and each has a dictionary entry that says what it contains and what it does not.
• A WBS fixes promised scope up front, a Product Backlog holds scope that emerges as the team learns, and many projects keep the backlog under one branch of a WBS.