Describe the stages of the systems development life cycle (analysis, design, development, testing, implementation and evaluation/maintenance) and explain why a structured process is used.

What this dot point is asking

WJEC asks you to describe the structured process used to create a new digital system, the systems development life cycle (SDLC), in the correct order, and to explain why following such a process matters. The exam form is "describe the stages in order" or "explain why stage X is important", so you must know the stages, their sequence and the purpose of each.

Why a structured process is used

Building a system without a plan risks expensive failure.

Analysis and design

The first two stages decide what to build and how.

Getting these right matters most, because an error in the requirements or design carries through every later stage.

Development and testing

The middle stages build and check the system.

Implementation, evaluation and maintenance

The final stages deliver and look after the system.

Following the cycle

The exam rewards applying the stages to a scenario.

Testing with the right data

Because testing is so heavily examined, it helps to know how it is done well. A thorough test plan uses different kinds of test data: normal data, which the system should accept (for example an age of 25); boundary data, the values at the edge of what is allowed (such as the lowest and highest valid age); and erroneous (invalid) data, which the system should reject (such as a letter typed into an age box). Choosing data of each kind checks that the system works for ordinary use, copes correctly at the limits, and handles mistakes safely rather than crashing. Saying not just "the system is tested" but "tested with normal, boundary and erroneous data" shows the depth markers look for in this stage.

Why this matters

The SDLC is the professional way digital systems are built, and it directly underpins the NEA components, where you analyse a brief, design a solution, create it, test it and evaluate it, exactly the same cycle. Understanding why each stage exists, especially why analysis and testing are so important, explains why rushing development leads to systems that fail or do not meet needs. It is also the framework employers use, so it links classroom theory to real digital projects.