Drawing a structure diagram from a scenario

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Where do you write the name of the whole problem when drawing a structure diagram?

A In the bottom boxes

B In the top box

2. A washing machine program is the top box. Which is a sensible box on the next level down?

A Fill drum with water

B Washing machine

3. Which box name is clearer for a quiz game with scoring?

A Add 1 to score

B Do stuff

4. When do you stop splitting a box in a structure diagram?

A When the box is one simple task

B When the diagram fills the page

5. How should you build a structure diagram from a scenario?

A Start with the smallest tasks at random

B Start at the top and split level by level

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Washing machine control program (top box)		AThe whole problem is split into three sub-problems on the next level down
2Quiz game -> Ask questions, Check answers, Update score		BThe whole problem is named in the top box of the structure diagram before it is split into sub-problems
3Keep splitting a box until it is one simple task, then stop		CThe box names are vague, so nobody can tell what each sub-problem does. Use clear names such as Fill drum, Wash clothes and Spin dry.
4Use a clear box name that says what the box does		DFill drum with water
5Washing machine -> Do things, Other stuff, Part 3		EThe diagram is split too far. Add 1 to score is already a simple task, so splitting it further adds nothing useful.
6Quiz game -> Add 1 to score -> Press the + key -> Move finger to key		FUpdate score -> Add 1 to score (stop here)

Definitions

top-down design

Fill in the Blanks

Complete each line of code by filling in the missing parts.

PROCEDURE WashingMachine ____ FillDrum CALL Spin

CALL AskQuestion CALL CheckAnswer PROCEDURE ___________

PROCEDURE Spin OUTPUT "Drum spinning" ____________

PROCEDURE AddScore score _ score + 10 ENDPROCEDURE

_________ QuizGame CALL AskQuestion CALL AddScore

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A Program

B Ask questions

C Check answers

D Show final score

Question 2

A Washing machine program

B Fill drum with water

C Do things

D Spin and drain

Question 3

A Quiz game

B Ask questions

C score = score + 1

D Show final score

Question 4

A Washing machine program

B Rotate valve by 1 degree

C Wash clothes

D Drain and spin

Question 5

A Spin cycle

B Fill drum

C Wash clothes

D Spin dry

Answer Key

Drawing a structure diagram from a scenario

Section A: Quick Questions

B — In the top box

A — Fill drum with water

A — Add 1 to score

A — When the box is one simple task

B — Start at the top and split level by level

Section B: Match the Pairs

Washing machine control program (top box) → The whole problem is named in the top box of the structure diagram before it is split into sub-problems

Quiz game -> Ask questions, Check answers, Update score → The whole problem is split into three sub-problems on the next level down

Keep splitting a box until it is one simple task, then stop → Update score -> Add 1 to score (stop here)

Use a clear box name that says what the box does → Fill drum with water

Washing machine -> Do things, Other stuff, Part 3 → The box names are vague, so nobody can tell what each sub-problem does. Use clear names such as Fill drum, Wash clothes and Spin dry.

Quiz game -> Add 1 to score -> Press the + key -> Move finger to key → The diagram is split too far. Add 1 to score is already a simple task, so splitting it further adds nothing useful.

Section C: Definitions

top-down design — Name the whole problem in the top box, then split it into sub-problems level by level until each box is one simple task. Use clear box names.

Section D: Fill in the Blanks

PROCEDURE WashingMachine
  CALL FillDrum
  CALL Spin

CALL AskQuestion
CALL CheckAnswer
PROCEDURE CheckAnswer

PROCEDURE Spin
  OUTPUT "Drum spinning"
ENDPROCEDURE

PROCEDURE AddScore
  score ← score + 10
ENDPROCEDURE

PROCEDURE QuizGame
  CALL AskQuestion
  CALL AddScore

Section E: Spot the Error

A — The top box must name the whole problem clearly. 'Program' is too vague. It should be something like 'Quiz game'.

C — 'Do things' is not a clear box name. A box should say exactly what the task is, such as 'Wash clothes'.

C — Box names in a structure diagram describe tasks in plain words. They are not lines of code. It should be 'Update score'.

B — This is far too detailed for a level 2 box. Split only as far as needed, so keep the box at the sub-problem level: 'Fill drum'.

A — The top box must name the whole problem, but 'Spin cycle' covers only one part. It should be 'Washing machine program'.