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In the classroom
Misconceptions
There are two common misconceptions relating to the
use of computers to control external events:
- Misunderstanding what the computer does and controls. If you tell
a computer to draw a line (for example FD 100) then the computer is
busy all the time that the line is being drawn, and can only do another
instruction once after it has finished drawing. If however you tell
the computer to turn on a light (for example SWITCH ON 1) then once
the light has been switched on, the computer is free to do another instruction
- it is not busy all the time that the light is on. The misconception
here is the belief that the computer is keeping the light on,
rather than that the computer switches the light on (and off).
The computer only changes states - not maintains them.
- Not understanding that the computer processes instructions sequentially
rather than in parallel. This is seen when, for example, pupils wish
to run an ambulance with flashing lights. They may write one procedure
(with an infinite loop) to make the lights flash and another to control
the ambulance. They want the computer to start the first procedure and
then begin the second. This will not work because the computer will
never leave the first procedure. The misconception is that the computer
can process more than one set of instructions at once.
For misconceptions relating to pupils' use of Logo
see the misconceptions section of the 'Logo and
on-screen control' page.
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Classroom examples
A key point when introducing control is to stress
that computers are inherently stupid - they will do what they are told
and only what they are told. Jane Challis developed a simple, quick
(5 min) and very effective activity to illustrate this. You can read the
details on the worksheet she
produced to explain the activity to other BTs.
Many secondary schools use Logicator for control
work - especially in Design and Technology lessons. You should visit their
website, not least for its list
of projects. You can also download
a demonstration version of the software which will run a series of example
flow-sheets.
See also the 'Control'
page of DigitalBrain's London Grid for Learning site, and decide how much
of this is really applicable to KS4.
For examples of what can be achieved with primary
school pupils, visit the Ambleside School Robo-Zone
which also has a number of useful links.
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Teaching point
In this session you are using much more equipment
than in most IT lessons. In addition, most of this equipment is both small,
expensive and coveted by many pupils. How are you to ensure that all the
equipment handed out is returned? This is very important - you would not
be popular if every time you did this lesson, equipment went missing.
You should discuss ways in which to achieve this with science BTs in your
school - they face similar problems in many lessons.
A common variant on this theme is that many schools
have adopted procedures to stop pupils removing mouse balls - for example
handing out the balls at the start of lesson and taking them back at the
end, or requiring pupils to leave the mouse with the ball facing up so
that the teach can check they are all still there before dismissing the
class.
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Other Resources
The DfEE Schemes of Work
You should look at the following units of the DfEE
schemes of work:
Key Stage 2: unit 5E, Controlling
devices; unit 6C, Control
and monitoring - What happens when...?;
Key Stage 3: unit 12 Control
systems.
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Books/Papers
See chapter 9 of Jean Underwood's book 'Computer
based Learning: potential into practice' (Institute library reference
Loyx UND).
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