Monday, May 25, 2015

CSI Science: Case of the Kidnapped Cookies Day 3

This post is the fourth in a series of posts about a CSI program I ran at our library.  You can read the background information here and here and here.


Day 3 found us analyzing the red marks on the ransom note envelope. It was (somewhat mysteriously) determined that the red marks are lipstick and lipstick samples from each suspect have been collected.




This is the only part of the unit that requires you to gather your own materials.  The kit comes with one lipstick sample, and it's necessary to come up with 3 additional samples, as well as some acetone to act as solvent.  This was the only part of this product that I found frustrating.  For all of the other materials included, it seemed silly that the lipstick was not.  It wasn't terribly hard to find inexpensive lipstick to use for the activity, but once you remove a chunk of the lipstick to have available for testing, it makes the rest of the lipstick fairly useless (and there's a lot of it left).

I'd recommend having your students perform a different chromatography experiment prior to this investigation (a simple black marker chromatography works great). The results of our lipstick chromatogaphy were basically all the same, and these students, being unfamiliar with the process, were looking for differences that just weren't there.  I think that if they had some background with the process, they'd better understand what different results look like (and how fun it can be to watch the colors separate).
Some of our chromatography strips.

The best part of this activity was the container provided to run the chromatography in.  It was a small plastic container, like you might get in the deli of a grocery store.  At first I was very skeptical of how it work, but it turns out, it was great!  There's a small ridge in the bottom of the container, and you can prop the chromatography paper strips up along that ridge.  You only need a very small amount of solvent, and you don't have to mess around with trying to suspend the paper strips from a pencil and trying to get height of the strips and the height of the solvent appropriately aligned.  I'll definitely try it that way again!


After we finished the chromatography, some students worked on putting their word-by-word Spanish translation together into something that made sense and others worked on determining which newspaper(s) the letters on the ransom note had come from.

Throughout the meeting (and all the others for that matter), the students regularly returned to the suspect bios to compare what new information they'd learned with the information about the suspects.


*****
The Case of the Kidnapped Cookies Kit was provided to me at no cost, for use with a group of students at my library.  I was not compensated by Educational Innovations in any other way, and all opinions expressed are my own.

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