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Class 7 · Society and design

Break a big job into parts: a class festival

"Organise a class mela" sounds huge. Where do you even start?

What you will learn: Decompose a big task into smaller tasks with order and owners.

Small test at the end: scroll down to the end of this page for five short questions that check what you have learnt. Tap an answer, then press Check answer. Go to the questions ↓

Jump to: Check yourself · For grown-ups · For teachers

Safety first

Plan only. Grown-ups run any cooking, wiring or money.

Keep it safe:

  • This is a planning activity: plan only, with no real cooking, electrical work or money handling unless a grown-up runs it.

You will need

  • Paper and a pencilA large sheet works well.
  • A real or pretend eventA class mela, a sports day, a family function.

Time: About 40 minutes.

The story

The teacher announces, "Class 7B, you will organise this year's mela!" Everyone cheers, then goes quiet. Tanmay wants to start making posters right now. Tara asks, "Posters for which day?" A big job can feel impossible. What if you broke it into smaller parts?

The idea

Decomposition means breaking a big problem into smaller parts that can each be done one at a time.

Keep breaking a part down until each task is small enough for one person or pair to do.

Some tasks depend on others: posters cannot be made until the date is fixed. Put those tasks in order.

Give each task an owner (who does it) and a time (when it must be done).

A tree diagram. At the top: hold a class mela. Below it three tasks: 1, fix the date; 2, plan stalls; 5, clean-up team. Under fix the date is 3, posters, which happen after the date. Under plan stalls is 4, money box and price list.Breaking down "Hold a class mela"thenthenHold a class mela1. Fix the date2. Plan stalls5. Clean-up team3. Posters(after the date)4. Money boxand price list
A tree diagram. At the top: hold a class mela. Below it three tasks: 1, fix the date; 2, plan stalls; 5, clean-up team. Under fix the date is 3, posters, which happen after the date. Under plan stalls is 4, money box and price list.

Worked example

Class 7B plans a mela

  1. Big job: "Hold a class mela."
  2. Parts: fix the date, plan stalls, make posters, organise money, clean-up.
  3. "Plan stalls" was still big, so they broke it down: choose 4 stalls, list what each needs, find two people for each stall.
  4. Order: the date first, because posters need it. Clean-up last.
  5. Each task got an owner and a deadline on a chart.

A huge job became small tasks in order, each with an owner.

Try it

  1. Write the big job.

    Put it in a box at the top of the page.

  2. Break it into parts.

    Write 4 or 5 parts underneath, each in a box.

  3. Break down big parts.

    If a part is still too big for one person, split it again.

  4. Find the order.

    Which tasks must wait for others? Draw an arrow from the first to the one that waits.

  5. Add owners and times.

    Next to each small task, write who does it and when.

What you make (paper or offline)

Your task breakdown

A tree diagram breaking a class mela into ordered tasks.Breaking down "Hold a class mela"thenthenHold a class mela1. Fix the date2. Plan stalls5. Clean-up team3. Posters(after the date)4. Money boxand price list
A tree diagram breaking a class mela into ordered tasks.

A tree from the big job down to small tasks.

Arrows showing which tasks must wait for others.

An owner and a time for every small task.

Make it on paper. Keep it with you. Nothing to upload.

Check yourself

Five questions about what this page teaches. Choose an answer and press Check answer, or open "See the answer and why". Nothing is saved or sent: your choices stay on this screen and disappear when you leave or reload the page.

  1. Question 1 of 5What does decomposition mean in planning?

    See the answer and why
    • A. Throwing away the plan and starting again Not this one. Decomposition keeps the plan and splits it into parts.
    • B. Letting food rot Not this one. In science that is one meaning of the word, but in planning it means breaking a problem into parts.
    • C. Doing the whole job alone in one go Not this one. Decomposition is about splitting the work up.
    • D. Breaking a big problem into smaller parts Correct. Smaller parts can be done one at a time and shared out.
  2. Question 2 of 5Which task must happen before the posters can be made?

    See the answer and why
    • A. Fixing the date Correct. The posters need to show the date, so it must be fixed first.
    • B. Taking down the stalls Not this one. That happens after the mela.
    • C. Counting the money taken Not this one. Money is counted on or after the day, not before posters.
    • D. Cleaning up after the mela Not this one. Clean-up happens at the end, after the event.
  3. Question 3 of 5"Plan stalls" is still too big for one person. What should you do?

    See the answer and why
    • A. Give it to the whole class with no owner Not this one. Without an owner, everyone may think someone else is doing it.
    • B. Break it into smaller tasks, such as choosing stalls and listing what each needs Correct. Keep splitting until each task is small enough for one person or pair.
    • C. Do it last, after clean-up Not this one. Stalls must be planned before the event, not after.
    • D. Leave it out of the plan Not this one. Then there would be no stalls at the mela.
  4. Question 4 of 5Why give every task an owner?

    See the answer and why
    • A. So that the owner can do every task Not this one. Each owner does their own task, not all of them.
    • B. So everyone knows who is doing it and nothing is forgotten Correct. A named owner makes sure each task gets done.
    • C. Because tasks without owners are faster Not this one. Tasks without owners are often forgotten.
    • D. So you can blame someone Not this one. The point is to share work clearly, not to blame.
  5. Question 5 of 5Tasks: A "book the hall", B "decorate the hall", C "choose the date". Which order works?

    See the answer and why
    • A. B, then A, then C Not this one. You cannot decorate a hall you have not booked for a date not chosen.
    • B. B, then C, then A Not this one. Decorating must come after booking.
    • C. C, then A, then B Correct. You need a date to book the hall, and the hall before decorating it.
    • D. A, then C, then B Not this one. Booking needs a date first.

Think back

Which task had to wait for the most other tasks?

Which part was hardest to break down?

Investigate further

  • Use decomposition to plan your homework for a week.
  • Break down "cook a meal" with a grown-up. Which steps can happen at the same time?

For grown-upsTap a heading to open it. The safety notes are at the top of the page.

Before you start
  • Choose a real or pretend event the child knows well.
Questions that help
  • "Is this task small enough for one person?"
  • "What has to happen before this?"
What's really going on

Decomposition is a key idea in computing and project planning: big problems become manageable when split into parts with a clear order.

Showing which tasks depend on others prevents last-minute surprises.

Other ways to do it
  • Plan a birthday celebration at home.

For teachersLearning aims, classroom ideas and what to look for.

Learning aims
  • Decompose a large task into ordered subtasks.
  • Identify dependencies and assign owners.
Subject links
  • Computing: decomposition.
  • Social science: cooperation and planning.
  • Mathematics: ordering and timelines.

These links are general. They have not been checked against a specific board syllabus.

In the classroom
  • Groups plan the same event; compare how they split it and which dependencies they found.
What to look for
  • Tasks small enough for one owner.
  • Dependencies shown in a sensible order.
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