3.3.1

• What is a Flowchart?

• Why are they used?

• How to draw them.

• Diagrams are great for helping people understand how a system works.

• However, for those who have no idea how to create a system (generally the customer!) a more simplified method of helping them understand what the system does needs to be used.

• Flowcharts are simplified diagrams which show basic input, output, decisions and processes.

• Because they are simplified diagrams they can only be used to show a generalised overview of the system or the functions within it.

You can use any symbols that you like...as long as you have a key and stick to it...but these are the more common symbols used.

You can see them in the Shapes option in MS Applications...

OutputOutputProcessProcess

InputInputStart/EndStart/End

DecisionDecision

StartStart

Add water to kettle

Add water to kettle

Is it full?Is it full?

Turn on power

Turn on power

Heat waterHeat water

Is water boiling?Is water boiling?

Turn off power

Turn off power

EndEnd

Yes

No

Yes

No

• Produce a data flow diagram which:– Controls a set of traffic lights over a bridge which

only allows traffic to go over it in one direction at a time.

– Lifts a barrier if it senses a car is stationary on its weight pad and also if the driver has taken a ticket.

• Go to the online text book or to page 38 of the text book...

• You will find an example scenario and an activity...

• Complete the activity.