📚 Unit Plans→Computational Thinking→Decompose and Model
Years 7–8Hangarau / Technology

Unplugged Computational Thinking Seminar · Lesson 2: Decompose and Model

Before we code a complicated idea, which smaller problems do we actually need to solve?

Unplugged Computational Thinking Seminar · Lesson 2

Seminar focus: break the problem down

Ākonga split a large task into parts small enough to describe exactly, and argue about where the boundaries should fall.

  • Unplugged Seminar move: Decomposition on paper, defended to the group
  • Evidence it produces: A part-list where each part can be described without referring to the others
Other teaching approach: Creative Coding Studio →

Lesson at a Glance | Te Hōtaka

Lesson Overview | Tirohanga Whānui

Using the challenge “run a class showcase”, ākonga split one vague goal into manageable parts, model one part as input–action–output, and test whether another pair can follow it.

Ngā Whāinga Ako | Learning Intentions

  • Decompose a broad problem into smaller tasks.
  • Model a task using inputs, actions and outputs.
  • Use abstraction to remove detail that does not affect the solution.

Do Now: “Organise the showcase”

7 min

Individually list everything hidden inside this instruction: organise a class showcase for whānau. Compare with a partner and circle the three items without which the event could not run.

Activity 1: Build a problem tree

15 min
  1. Write the goal at the top: A visitor can find, view and respond to each project.
  2. Create four branches: welcome, navigation, project display, feedback.
  3. Under each branch, add tasks small enough for one person to complete.
  4. Draw dependencies with arrows. For example, a project needs a name before the navigation list can be finished.

Test: Can every leaf task begin with a clear action verb?

Activity 2: Input → action → output

18 min

Choose the “visitor feedback” branch and model it.

Input

A visitor selects a rating from 1–5 and types one short comment.

Action

The system checks that a rating is selected, then saves the response.

Output

The visitor sees “Kua tae mai / Response received” and the class receives the result.

  1. Copy the three-column model for a different branch.
  2. Underline information the system must know.
  3. Cross out decorative detail that does not change the action or output.
  4. Write one question that your model still cannot answer.

Activity 3: Model relay

13 min
  1. Swap models with another pair without explanation.
  2. The receiving pair writes the first three instructions they would build.
  3. Return the model. Its authors mark one clear instruction and one hidden assumption.
  4. Revise the model so the hidden assumption becomes an input, action or stated limit.

Manaakitanga: Feedback describes the model’s effect on the user, not the author’s ability.

Exit: Keep or hide?

7 min

Write one detail your model must keep, one detail it can hide for now, and why. Finish: “Decomposition will help us build our design because…”

🎯 Curriculum Alignment
Designing and developing an outcome through spatial and product design, materials, foods, biotechnology, systems, or digital tools

Ākonga plan the components of a later digital outcome. See the evidence map.

📦 Materials & Resources

Resources already provided: the showcase scenario and model above. Supply A3 paper or a shared slide, sticky notes and markers.

📊 Assessment and Success Criteria

Paearu Angitu | Success Criteria: I can split a goal into actionable parts, label input/action/output, and justify one detail I removed. Keep the revised model as formative evidence.

♿ Inclusion, entry and extension

Entry: Provide the four main branches and picture cards to sort. On-level: Require dependencies and a complete three-part model. Extension: Identify an edge case such as missing feedback or duplicate project names. Chunked sticky notes reduce executive-function load; oral explanation or drag-and-drop cards are valid alternatives.

📋 Teacher Planning Snapshot

Do not let groups design the whole event. The goal is to practise decomposition, then zoom into one component. Lesson 3 turns the same input–action–output thinking into a triggered, ordered sequence — on command cards, or in Scratch if devices are available.

📚 Sources and teaching basis

Computational-thinking decomposition is taught through a local, collaborative design problem. Whanaungatanga is visible in dependency mapping: parts and people work in relationship, without reducing mātauranga Māori to a computing metaphor.