Chemistry lab partners Octavia Blount and Bill Schneider -- both teachers -- were ready for the day's experiment. Safety glasses protected their eyes. Blue latex gloves fit snugly on their hands.

All the standard equipment -- mortar and pestle, glass beakers and test tubes -- was spread out on their stretch of a long black granite countertop.

The idea was to take on the persona of a forensic chemist -- the person whose job it is to identify the unknown white powder that could be an illegal substance, just like on a TV cop show.

All around them, fellow teachers were solving the same riddle, a kind of chemistry class whodunit.

"This," said Blount, speaking of her own students, "will grab their ...