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Fingerprints, ink, and a mysterious white powder

This was a very busy class! First we talked about fingerprints; how they can be used, and misused, in a criminal investigation. And we studied our own, looking for arches, whorls and loops. What's your predominant pattern? Ask your kid to show you how to get your own fingerprints!

We talked about toeprints too! Yes, we leave toeprints wherever we go, as long as we are barefoot. Beware!

And then we discussed ink, a topic that's more fascinating than you might imagine. We discovered that ink is not made of one pigment but many, and that those pigments can be easily separated using the technique of chromatography. And that's exactly what we did.

Look at one of our beautiful chromatograms! Ink is just starting to separate. Who would have guessed that brown has grey and pink and yellow in it.

The skills of fingerprinting and ink analysis are going to be very useful the day of the actual investigation, coming up in just a couple of weeks. The police say they lifted a partial fingerprint from the crime scene and received a handwritten note!

Everybody was so good and worked so hard that we managed to squeeze in a third activity: chemical analysis of an unknown substance, basically, identifying a substance by testing how it reacts to different known chemicals. We are not sure whether the police found any suspicious powder at the crime scene, but we wanted to be prepared.

We tested three mystery powders with vinegar, water, and iodine and the kids were able to tell us exactly what each one was. Smart detectives!

Next class we'll be extracting DNA and learning how to interpret and compare DNA profiles. Stay tuned!

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