Start with Common System Functions For any system (like online examination), think in terms of core business processes:

Level 1 DFD - Break down your context diagram into major processes:

User Management (login, registration, authentication)

Content Management (questions, exams, results)

Examination Process (take exam, submit answers)

Reporting/Analytics (generate reports, view results)

Level 2 DFD - Decompose Each Process Take one Level 1 process and break it further:

Example: "Examination Process" becomes:

Validate student eligibility

Display questions

Capture answers

Calculate scores

Store results

Practical Exam Strategy When stuck, use this template:

Input processes (what comes into the system)

Processing/Business logic (what the system does)

Output processes (what goes out)

Storage interactions (read/write to data stores)

Quick DFD Rules Each process needs inputs and outputs

Data flows between processes, not between external entities

Every data store should be accessed by at least one process

Number processes: 1.0, 2.0, 3.0 (Level 1), then 1.1, 1.2, 1.3 (Level 2)