© boardworks ltd 2003 1 of 17 flow charts control for more detailed instructions, see the getting...

© Boardworks Ltd 20031 of 17

Flow Charts

Control

For more detailed instructions, see the Getting Started presentation.

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Step by step

When completing a task, you need to ensure that the instructions to follow are step by step.

Imagine you are doing something new and are following a list of instructions. You will need these instructions to be in order.

An ordered list of instructions is called a sequence.


Explain to an alien how to make a cheese sandwich.


Understanding the symbols

A set of instructions for a task can be represented using diagrams.

Instructions to computers can be summarized by using a flow chart.

A flow chart is a diagram that uses special symbols and language.

Each symbol has a specific meaning and purpose, and there are certain words that the computer expects to see.


In a few words

Now that you know what the symbols are, try and complete the diagram on the next slide.


There are special software programs, like Flowol, which allow you to create flow charts that control input and output devices to mimic a real-life situation.

For example, you can create flow charts to mimic a pelican crossing, a car park barrier or a home alarm system.

Flowol screen shots by kind permission of Data Harvest: Keep IT Easy, KITE.


On occasions, parts of some flow charts are designed to continue checking and rechecking a situation to see if there are any changes.

Going loopy

For example, checking to ensure that a greenhouse maintains a specific temperature.

The sensor keeps checking for a change in temperature to turn on heat (if the temperature decreases) or open windows (if the temperature increases).

This process of going round and round is called a loop.


yes

no There are two loops

Think how much easier this is than having to check manually

all the time.

Going loopy – an electronic shop door

Start

Is somebody at the door?

Open door

Close door


Going loopy – temperature in a greenhouse


What makes it great?

Imagine you are designing a water ride for a theme park. What happens on the ride?

You can create diagrams for more complicated systems.

people will be going up a ramp in a boat

then they slide down into a pool of water

a photograph is taken whilst they are on the ride

water is sprayed from the sides to get them wet.


What control devices would you need to make the slide work efficiently?

What inputs, outputs, processes and decisions are required?

How can you ensure that the ride is safe and there is no chance of boats colliding?

Have a look at some suggestions on the next slide.


When you complete the system you need to check whether you have been successful in your solution.

What methods could you use to show how well your system worked? You could try these:

ask yourself ‘What was the original aim of the system?’

show your ideas to others for a different point of view

could your design be improved?

what would you try to improve?

what does it have to do in order to function safely?

would you use it?


Summary

What can I remember?

An ordered list of instructions is called a sequence.

Instructions to computers can be summarized by using a flow chart.

A flow chart is a diagram using special symbols and language.

Loops can be created to enable software to keep checking and rechecking.

There are various ways to check whether a system is successful.

© boardworks ltd 2003 1 of 17 flow charts control for more detailed instructions, see the getting...

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