Chromatography

Black is black, right?  When you look at a black marker, you would think that black is the only color that makes up the black ink.  However, if you break the ink down, you would be surprised to see the different colors that make up the black ink.  This process is called chromatography.  Chromatography is a process where you separate and detect chemical compounds.
 
When I first started teaching chromatography, I did the standard marker and coffee filter experiment.
http://www.exploratorium.edu/science_explorer/black_magic.html
 
Then I found this project for chromatography and have been teaching it this way ever since.  The kids have a great time "designing" their own t-shirts and they are learning science concepts at the same time!

http://www.stevespanglerscience.com/experiment/sharpiepenscience
 
Candy is another fun way to experiment with chromatography.
http://scifun.chem.wisc.edu/homeexpts/candy.htm