The stray strand of electric wire is barely visible to the naked eye.
However, Gary Randall's students can see clearly how it could cause a big problem, creating a short circuit that would sabotage their electronics project. They are watching a larger than life demonstration by their teacher, in which the wayward wire is magnified in a huge image that covers the classroom wall. Gary is using a visualiser - a presentation device that incorporates a camera and allows the whole class to explore the tiniest details. It has transformed his demonstrations, and is doing much to help students avoid the pitfalls that await them in their major GCSE project.
Gary is head of technology at Barking Abbey School in Barking, Essex, and the project is part of the electronics module in GCSE systems and control.
The aim is to design and manufacture a product that will create a light display which young people can watch while they are listening to music at home. "Students are really fired up by it," he says.
The exercise counts for 60 per cent of the overall GCSE mark, and spans Years 10 and 11. Students start by researching the products currently on the market and asking would-be buyers what they look for in a light show.
They then investigate the different kinds of circuit that can create flashing or pulsing lights, and go on to design and produce their own version. Gary says: "They tend to choose a programmable chip - a peripheral interface controller (PIC) - as the system for controlling the light show.
You can buy the circuit boards to run these chips, but our students design and make their own boards, using software to help draft the design and control the milling machines that manufacture the boards. They then populate the board with components."
It is at this stage that the visualiser comes into its own. Gary says:
"Students have a printed circuit board, with 70 or 80 holes made for the legs of the components. They have a circuit diagram they can refer to, but it is so much better if I can give them live demonstrations at different stages in production, and show exactly how to prepare cables and solder the various components into place.
"It is very difficult for students to get close enough to see the fine detail. I used to give one-to-one demonstrations to the 20 pupils in the class, which took a lesson and a half. Now I can demonstrate to the entire group in 10 minutes - and I feel more confident that everyone understands what I am getting at. The visualiser is really marvellous."
When he places a circuit board on the platter of the visualiser, the overhead camera captures the view, sending it via the classroom data projector to a screen on the wall. Gary says: "I can take a 20 millimetre square of detail on the circuit board and show it as a 2.5 x 2 metre image that fills the whole wall. I take students through various pitfalls - I can show an example of a badly prepared cable, with a tiny strand of wire going astray, and explain how that would cause a short circuit and create serious problems. Everything is so big, so bright, so clearly visible. We also get a dialogue going, with everyone reaping the benefits in a way that wouldn't be possible if students were having one-to-one demonstrations or watching a video."
The visualiser and projector are linked to the classroom computer, and Gary can switch to a view of the PC screen during his demonstrations. "I can show a circuit diagram, to help students relate what is on the diagram to the actual components on the board. I could also run software that would simulate how current would flow."
Images from the visualiser can be captured and stored on the PC or school network for future use, and Gary plans to record his future demonstrations as digital videos, which will help students recapitulate or catch up on lessons they have missed.
He and his colleagues are turning to the visualiser for an increasing number of tasks, and finding that it can inject new life into lessons. He says: "If you wanted to show a fine example of engineering from the workshops, you had to pass a component round the class. Each student would hold it for a few seconds and try to look intelligent, then pass it on. Now you put it on the visualiser, and that immediately encourages a bit of banter - students begin asking questions and making comments. You can zoom in really close, capturing anything from the structure of different timber-based materials to the cutting edges on tools."
* Barking and Dagenham LEA www.bardaglea.org.uktestbed
* Barking and Dagenham's ICT Test Bed project uses Samsung SDP-950 visualisers, from pound;1,395 www.samsungpresenter.com
* Gary Randall's students use Techsoft PCB Design Make software for designing printed circuit boards, and Techsoft 2D Design software for controlling the milling machines that manufacture the boards www.techsoftuk.co.uk
Tel: 01745 535007 Above: Gary Randall makes use of the visualiser to expore circuit boards with GCSE groups