Simulation - A Practical Guide to Teaching Computing and ICT in the Secondary School - page 111

influences the behaviour of the system. The signals are either analogue or digital in
nature, and a device to convert them from one format to the other may be required
(Analogue to Digital Convertor [ADC]/Digital to Analogue Convertor [DAC]).
Both feedback and ADC/DAC are pivotal concepts and need to be introduced
with care. Incremental or scaffolded learning and teaching, through the use of
analogy and/or examples with which pupils will be familiar is a good way to
do this. For instance, you may choose to make reference to thermoregulation, to
explain to your pupils the connections between the parts of a Control system.
Thermoregulation is the ability of an organism to keep its body temperature
within certain boundaries, even when the surrounding temperature is very
different. In human beings this means that receptors in the skin sense external
temperature (Input). The hypothalamus in the brain compares this with body
temperature (Process). If there is a significant difference, e.g. it is cold outside, a
signal is transmitted that induces shivering, which generates heat (Output). This
is an unconscious action that continues until the difference is no longer a threat,
or further action is required (Feedback). This approach also strengthens the notion
that you can teach some aspects of Computer control without access to expensive
equipment and programmes.
Task 6.6
Analogies
How would you explain the following using an exemplar and/or an analogy?
Input; Process; Output; Open/Closed Loops; ADC/DAC
It is important to make pupils aware that although the discrete parts of a Control
system do exist separately in some devices, they are difficult to identify; e.g. the
microprocessor in an automatic kettle, or a car engine management system. Pupils
also encounter many features of a Control system, particularly input and output
devices, in different subjects; e.g. Design and Technology, Science. They may not
transfer this knowledge readily to Computing. Therefore, you need to help them
make links by reinforcing what they should already know. Some of the Control
kits available for use in schools have an array of input and output devices that are
useful in this context.
Task 6.7
Sensors
There are a multitude of sensors and actuators used in Control systems. Identify
which devices you regard as the most important, to introduce to children who
are encountering the concept for the first time, and state how you would do it.
The word 'Control' is not mentioned explicitly in the current Computing
programmes of study at Key Stages Three and Four. However, it is hard to
imagine Computing being taught without some significant examination of this
area because it: