Year 11 · Computer Science · Summer 2 · After the exams

Course evaluation

TheoryPresent ▶

What this lesson covers

7.1 The program development life cycle

Cambridge IGCSE Computer Science 0478 · Topic 7: Algorithm design and problem-solving · Paper 2

You will learn to

Evaluate the course: what helped you learn, and what did not.
Identify the hardest topic and the most useful lesson, with a reason for each.
Suggest one change for next year's Year 11.

Success criteria

I can give one specific example of something that helped me learn.
I can name the hardest topic and say why it was hard.
I can write one clear, kind suggestion for next year.

The syllabus points for this section

Name the four stages: analysis, design, coding and testing.
Explain abstraction and decomposition in the analysis stage.
Name the design tools: structure diagrams, flowcharts and pseudocode.
Explain iterative testing during coding and testing with test data.

Key words

Say each word, then read what it means. Every one is in the glossary too.

Program development life cycle: The four stages of making a program: analysis, design, coding and testing.
Abstraction: Removing details that do not matter so you can focus on the ones that do.
Decomposition: Breaking a problem into smaller parts that are easier to solve.
Structure diagram: A top-down diagram that shows how a system is split into sub-systems.
Flowchart: A diagram of an algorithm using standard shapes joined by flow lines.
Pseudocode: A structured, code-like way of writing an algorithm that is not tied to one language.
Check digit: An extra digit calculated from the other digits, used to catch typing errors.
Normal data: Test data that should be accepted.
Abnormal data: Test data that should be rejected.
Extreme data: The largest and smallest values that should be accepted.

The explanation

Read it here, or open the study page below to go one step at a time with things to try.

Four stages, in order

The program development life cycle is the set of stages a programmer goes through to make a program.

There are four stages: analysis, design, coding and testing.

It is called a cycle because problems found in testing send you back to an earlier stage.

Stage	Question it answers	What is produced
Analysis	What must the program do?	A list of requirements
Design	How will it do it?	Structure diagrams, flowcharts, pseudocode
Coding	Can we build it?	Program code, tested as it is written
Testing	Does it work for all data?	Test results with test data

?Why?

Planning before coding is faster overall. A mistake fixed in the design costs minutes. The same mistake found after coding can cost hours.

!Watch out

Learn the four names exactly. Cambridge uses analysis, design, coding, testing. Words like 'planning' or 'making' do not earn the mark.

Analysis: understand the problem

In analysis you find out exactly what the problem is and what the program must do. These needs are the requirements.

Abstraction means removing the details that do not matter, so you can focus on what does.

Decomposition means breaking a big problem into smaller parts that are easier to solve.

e.g.Example

Problem: a school canteen wants a top-up system for student cards. Requirements: input the card number and amount, add the amount to the balance, show the new balance. Abstraction: the colour of the card and the student's hair colour do not matter. Keep card number, name and balance. Decomposition: read card → choose amount → take payment → update balance.

?Why?

Abstraction stops you wasting time on details that will not affect the program. Decomposition turns one scary problem into several small, easy ones.

Design, coding and testing

In design you plan how the program will work. You decompose further and use structure diagrams, flowcharts and pseudocode.

In coding you write the program. You test each part as you write it. This is called iterative testing: write a bit, test it, fix it, repeat.

In testing you run the finished program with planned test data to check it works for every kind of input.

e.g.Example

Canteen system: Design: a flowchart for 'take payment'. Coding: write 'update balance' and test it with one card before writing the next part. Testing: try a top-up of 10 euros (normal), -5 euros (abnormal) and the largest allowed amount (extreme).

!Watch out

Do not mix up iterative testing and final testing. Iterative testing happens during coding, part by part. Final testing uses a full test plan on the finished program.

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