Spot the missing arrow
A teacher says, "Students forget their passwords all the time. Draw how a reset works." You have symbols. Now you need to use them.
Reading a diagram and drawing one are two skills. Both start with the same question: what goes in and what comes out?
By the end of this lesson
Note
I can read a data flow diagram and complete one for a support system.
Key words
| Word | What it means |
|---|---|
| Data source | a person or system that sends data in |
| Data destination | a person or system that receives data out |
| Process | a step that does something to the data |
| Data store | a place where data is kept |
| Inputs | the data that goes into a process |
| Outputs | the data that comes out of a process |
The cells students fill in are left blank in this preview.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
How to read a DFD
Follow four steps.
- Find the sources and destinations. They are the edges of the system.
- Pick one source and follow its arrow.
- At each process, ask what comes in and what goes out.
- Note where the data is kept.
What the diagram says
Note
The user asks for a reset. "Check identity" reads the Account list. If the user is verified, "Make new password" saves a new password hash back into the Account list and sends a reset email. The email system is the destination.
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.