Software Development

What Software Development covers

Software Development is examined on component 01 of OCR Computer Science, Computer systems. 41 recall questions across 3 subtopics.

The 3 subtopics

Each one has its own page.

• The five development methodologiesRecall questions on the waterfall lifecycle, agile methodologies, extreme programming, the spiral model and rapid application development, the merits and drawbacks of each, prototypes, and what iterative development means.Open →
• Choosing a methodology: merits, drawbacks and fitRecall questions on choosing a development methodology for stated projects, whether waterfall is obsolete, customer involvement, the trade-off between documentation and speed, cost estimation, and what goes wrong when agile loses its architecture.Open →
• Writing and following algorithmsRecall questions on writing algorithms before code, pseudocode and flowcharts, trace tables, following short algorithms, divide-by-zero and off-by-one faults, syntax, logic and runtime errors, validation and verification, test data and subroutines.Open →

What you need to know

Answer each one before you reveal it.

Take Software Development further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• The waterfall lifecycle vs Agile methodologies

  The waterfall lifecycle: a sequence of stages each completed and signed off before the next begins. Agile methodologies: an approach delivering working software in short increments, expecting requirements to change.

• Extreme programming vs Rapid application development

  Extreme programming: an approach built on pair programming, constant testing and a customer on the team. Rapid application development: an approach built on prototypes shown to users and refined quickly.

• The spiral model vs A trace table

  The spiral model: an approach organised around repeated cycles that assess risk before each stage of work. A trace table: a table recording the value of each variable after every step, used to dry run by hand.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is a software development methodology, and why does one matter?

   Model answer

   An organised approach to building software that sets out what stages the work goes through, in what order, who is involved, and how progress and change are handled. It matters because software projects are large, involve many people, and fail far more often through poor organisation, misunderstood requirements and uncontrolled change than through anyone being unable to write the code.

2. 2

   Describe the waterfall lifecycle.

   Model answer

   A sequential model in which the project passes through a fixed series of stages, each completed and signed off before the next begins: feasibility study, requirements analysis, design, implementation, testing, and then installation and maintenance. Each stage produces documentation that feeds the next, and the flow is intended to be one way, like water falling from one step to the next.

3. 3

   State the stages of the waterfall lifecycle in order.

   Model answer

   Feasibility study; requirements analysis; design; implementation (coding); testing; installation, then ongoing evaluation and maintenance. Each stage is completed and approved before the next begins.

4. 4

   What are the merits of the waterfall lifecycle?

   Model answer

   It is simple to understand and to manage, because at any moment everyone knows which stage the project is in. Costs, timescales and staffing can be estimated in advance because the whole scope is fixed at the start. It produces thorough documentation at every stage, which makes long-term maintenance and handover to a different team much easier, and which is often required for auditing or safety certification. It also works well when the requirements genuinely are known and stable, and it needs less continuous customer involvement than the other approaches.

5. 5

   What are the drawbacks of the waterfall lifecycle?

   Model answer

   It assumes the requirements are fully understood before any code is written, which is rarely true. Because the client sees nothing working until near the end, misunderstandings are discovered very late, when they are most expensive to correct. Going back to an earlier stage is difficult and costly, so the model copes badly with changing requirements. Nothing usable is delivered until the whole project is finished, and heavy documentation absorbs time.

6. 6

   Describe agile methodologies.

   Model answer

   A family of approaches in which the software is built in a series of short iterations, each producing a working, tested increment of the product that can be shown to the customer. Requirements are expected to change and are re-prioritised at the start of each iteration in the light of feedback. Working software is valued over comprehensive documentation, and the customer is involved throughout rather than only at the beginning and the end.

What is inside Levo

Six ways to work the same material.

Software Development revision questions

What does Software Development cover in OCR A-Level Computer Science?

3 subtopics: the five development methodologies, choosing a methodology: merits, drawbacks and fit and writing and following algorithms. Each one has its own page with questions and model answers.

How is Software Development organised?

By the OCR H446 specification, subtopic by subtopic, so it matches the order you are taught it in.