Marcus L. Rowland (ffutures) wrote,
Marcus L. Rowland

Playing CSI

Every year the school where I work runs a two-day event to encourage year 9 kids (14-ish) to take up a career in science. The final part of it is a big forensic science investigation where they use some clues to find out who committed a murder. This involves testing fabrics to identify the material, chromatography of ink samples, testing chemicals, working out the height that blood drops have fallen from by measuring the diamater of the splatter, testing coffee for sugar, analysing a floppy containing suspect data, fingerprinting, and so forth. The investigation takes most of the morning, then they have to present the results and accuse the "guilty" teacher in the afternoon.

One of the things we've done the last couple of years is have them extract DNA from blood (actually pureed kiwi fruit with dye). When they give me a tube with the DNA in it (it looks like wooly fibres) I put a sample on a slide and put it into the "official DNA tester" then give them a "printout" of the suspect's DNA test, which is compared to results for all the teachers. The snag is that the "Official DNA tester" dosn't work - a real DNA analysis secup costs a couple of hundred thousand and takes a couple of days. So it needs to be a convincing fake.

The first year I used a data-logger of a type that they weren't familiar with and put one of the sensors over the slide and pretended it was doing something. Not very convincing.

This year I put the slide onto the stage of an Intelplay microscope (basically a webcam with microscope lenses), let them see the fibres on the window of an image capture program, then scrolled down the actual image that had already been prepared to show a representation of a DNA molecule before giving them the printout. Pretty, but it was a bit obvious what I was doing.

What I really need next time round is some sort of app (maybe just a prepared web page) that will show the camera input on one side and has some impressive-looking buttons which, when pressed, give the appearance of zooming in to the DNA and analysing it on an image below the first. This could be something as simple as an animated GIF. It doesn't necessarily need to print out since that bit will probably still be faked, but that could be a possibility.

Any suggestions on how to do this, remembering that I'm not exactly the best programmer or web designer in the world?

Question for Australian readers etc.: One of the experiments, taken from an Australian web site, was supposed to use "corn syrup" to make the perfect blood spatter mix. Snag is that the stuff doesn't seem to be on sale in the UK, can anyone tell me what this is in British terms? The stuff we used worked, but not as well as we would have liked.

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