What are the stages of the software development lifecycle, and how do the waterfall and agile approaches differ?
The software development lifecycle: the stages from analysis through design, implementation, testing, installation, evaluation and maintenance, and a comparison of the waterfall and iterative or agile development methodologies.
An Eduqas Component 1 answer on the software development lifecycle: the stages of analysis, design, implementation, testing, installation, evaluation and maintenance, the types of maintenance, and how the waterfall model compares with iterative or agile development.
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What this dot point is asking
Eduqas wants you to describe the stages of the software development lifecycle in order, state what happens at each, describe the types of maintenance, and compare the waterfall model with iterative/agile approaches, including when each is appropriate.
The answer
The stages of the lifecycle
Installation methods and maintenance
Waterfall versus agile/iterative
Examples in context
The SDLC is the backbone of professional software engineering, and choosing waterfall versus agile is a real decision teams make based on how stable the requirements are; safety-critical systems often lean towards rigorous, documented (waterfall-like) processes, while consumer apps lean agile. The Eduqas project (Component 3) explicitly rewards an iterative approach, building and testing in cycles and showing how feedback shaped the solution. The lifecycle ties together the analysis, design, testing and tools dot points in this module into one coherent process.
Try this
Q1. Name the lifecycle stage that checks the finished system against the original requirements. [1 mark]
- Cue. Evaluation.
Q2. State the difference between corrective and adaptive maintenance. [2 marks]
- Cue. Corrective maintenance fixes faults; adaptive maintenance changes the system to suit a new environment or a change in the law.
Q3. Give one situation where the waterfall model is the better choice than agile. [1 mark]
- Cue. When the requirements are well understood and stable from the start (for example a system implementing fixed legal rules).
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas 20196 marksDescribe the main stages of the software development lifecycle, in order, and state what happens at each.Show worked answer →
Award up to 6 marks, roughly one per stage correctly named and described:
Analysis: identify stakeholders, gather requirements and study the current system, producing a requirements specification.
Design: design the inputs, outputs, processing and data structures (data dictionary, algorithms, interfaces).
Implementation (coding): write the program in the chosen language from the design.
Testing: test with normal, boundary and erroneous data, fixing faults found.
Installation (deployment): install the system and convert from the old one (direct, parallel, phased or pilot changeover).
Evaluation: check the finished system against the original requirements.
Maintenance: correct faults and adapt the system over its life.
Markers reward the stages in a sensible order with a correct one-line description of each.
Eduqas 20215 marksCompare the waterfall model with an agile (iterative) approach to software development, giving one situation in which each is the better choice.Show worked answer →
Waterfall (up to 2 marks): a linear sequence of stages, each completed before the next begins, with thorough documentation; changes late on are costly. Best when requirements are well understood and stable from the start, such as a system with fixed legal rules.
Agile/iterative (up to 2 marks): development in short repeated cycles producing working increments, with frequent user feedback and easy accommodation of change. Best when requirements are unclear or likely to evolve, such as a new consumer app.
Comparison point (up to 1 mark): waterfall gives predictability and strong documentation but little flexibility; agile gives flexibility and early working software but less upfront certainty.
Markers reward the linear-stages description of waterfall, the iterative-with-feedback description of agile, and a suitable situation for each.
Related dot points
- Systems analysis: identifying stakeholders, gathering requirements (interviews, questionnaires, observation, document analysis), analysing the current system, the feasibility study and its factors, and writing a requirements specification.
An Eduqas Component 1 answer on systems analysis: identifying stakeholders, the fact-finding techniques for gathering requirements, analysing the current system, the feasibility study and its TELOS factors, and writing a requirements specification.
- System design: designing the inputs, outputs, processing and data structures, the use of flowcharts and pseudocode, the data dictionary, file and interface design, and specifying the hardware and software the proposed system needs.
An Eduqas Component 1 answer on system design: designing inputs, outputs, processing and data structures, using flowcharts and pseudocode, the data dictionary, file and interface design, and specifying the hardware and software the proposed system requires.
- Software engineering tools: the tools that support analysis, design, programming and testing, the role of an IDE in the development process, and version (source) control for managing changes and team collaboration.
An Eduqas Component 1 answer on software engineering tools: the tools supporting analysis, design, coding and testing, how an IDE supports development, and why version control manages changes, enables collaboration and allows rollback.
- Testing and correctness: the types of program error (syntax, runtime and logic), test strategies and test data (normal, boundary and erroneous), trace tables and dry runs, and validation and verification of input data.
An Eduqas Component 1 answer on testing and correctness: syntax, runtime and logic errors, choosing normal, boundary and erroneous test data, dry runs with trace tables, and the difference between validation and verification of input.
- Economic, moral, legal, ethical and cultural issues: the impact of computer science on individuals and society, the relevant UK legislation (Data Protection, Computer Misuse, Copyright and Freedom of Information), and ethical concerns such as privacy, surveillance and the digital divide.
An Eduqas Component 1 answer on the impact of computer science: the economic, moral, ethical and cultural effects on society, the relevant UK legislation (Data Protection, Computer Misuse, Copyright, Freedom of Information), and issues such as privacy, surveillance and the digital divide.
Sources & how we know this
- WJEC Eduqas GCE AS/A Level Computer Science specification (from 2015) — Eduqas (2015)