Lesson Notes By Weeks and Term - Senior Secondary 2

Term: 2^nd Term

Week: 7

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 2 periods each

Date:       

Subject:      Computer studies and ICT

Topic:-       System Development cycle IV

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. State the levels of system development life cycle
2. Explain each stage of the system development life cycle
3. Discuss the advantages and disadvantages of the system development life cycle

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, pictures, Data Processing for senior Secondary Education by Hiit Plc, WAPB Computer Studies for Senior Secondary II by Adekunle et  al, On-line Materials.

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

STAGES IN SYSTEMS DEVELOPMENT LIFE CYCLE

However, there are methods for developing information systems. The oldest and classical method of systems development life cycle (SDLC) is called the Waterfall Model. The waterfall SDLC is a sequence of stages that must be followed one after the other. Stage 2(two) can only begin when stage one is completed. Therefore, the output of each stage becomes the input for the next. These stages can be characterized and divided up in different ways, including the following:

1. Investigation stage: this stage involves the investigation of the existing system. The existing system is studied and evaluated to identify its problems and deficiencies. It involves gathering information about the existing systems. The information could be gathered through Observation (observing the system), Questionnaire (preparing questionnaires based on the existing system and give to the users to fill) and Interviewing (asking the users verbal questions about the system). The information gathered is used in a feasibility study. The aim of the feasibility study is to identify the problems and proffer feasible solution through a feasibility report. It also identifies how this problem is to be solved (either manually or computerized), when it is to be solved and why it should be solved. It defines the objectives and goals that the new system to be developed will achieve. The feasibility report is the main output of the investigation.
2. Systems Analysis stage: This stage starts with a more detailed investigation into the existing system. The same facts finding methods of observation, questionnaire and interview are used to gather end-users information such as data and procedures and processes. The data and procedures are analyzed to define the new system requirements. The new system requirements are defined addressing the deficiency in the existing system with specific proposals for improvement. The output of the analysis stage is the users’ requirements.
3. Systems Design Stage: At this stage the proposed system is designed. It involves layout plans for the physical construction, hardware requirements, operating systems, programming, communication, and security. The design describes the desired features and operations of the proposed system in detail, including screen layouts, business rules, process diagrams, flow charts, pseudo-code and other documentation such as data dictionary and so on. The system design stage produces the Systems Specification.
4. Systems Implementation stage: This stage is the stage where programs of the new system are written in the specified programming language in line with the systems specifications. It involves testing of all the new system and adjustments and corrections are made where necessary.
5. Systems Deployment: Here the system that was developed in stage 4(four) is put into use. It involves bringing all the different parts the proposed system together. All parts of the system is integrated and tested for errors, bugs and how they operate. It includes the installation and deployment. This is the stage where the software is put into use and runs the actual business.
6. Systems maintenance Stage: once the new system is deployed and running, it is subjected to exhaustive evaluation on how it is able to achieve its setup goals. Areas for improvement will be modified and enhanced. Sometimes the mistakes or errors can be detected. Procedures and processes may change. Thus the remaining life of the system is subject to changes, correction, additions, moves to a different computing platform and more. The system maintenance stage involves all the activities, processes and procedures required by the system to exist forever.

ADVANTAGES OF SDLC

1. Simple and easy to use
2. Easy to manage due to the rigidity of the model.
3. Phases are processed and completed one at a time works well for the development of smaller information systems where requirements are very well understood.
4. Provides guidelines for systems development as all the stages and activities are clearly outlined
5. Promotes consistency among systems development projects.
6. Reduces cost of managing different systems at different stages.
7. Helps in efficient allocation of resources to systems development projects.

DISADVANTAGES OF SDLC

1. Adjusting scope during the life cycle can kill a project.
2. No working software is produces until during the life cycle
3. High amounts of risk and uncertainty.
4. Poor model for complex and object-oriented projects.
5. Poor model for long and ongoing projects
6. Poor model where requirements are at a moderate to high risk of changing.
7. If followed slavishly. It can result in the generation of unnecessary documents.
8. It takes time to go through the whole long development cycle.

 EVALUATION: 1.Discuss each stage of the system development life                                     cycle         

2. Outline the advantages and disadvantages of the               system development life cycle.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively