Last fall, a Denver teacher, Daniel Powell, was charged with four counts of misdemeanor assault after a classroom fire seriously burned a student. Powell had lit a small pool of methanol to demonstrate its flame properties, then tried to add more methanol from a 4 L container, Chemical Safety & Hazard Investigation Board investigators said in September. The fire flashed back into the container, then jetted out to hit the student in the chest. Other students sitting nearby were also injured.

The charges against Powell have been dropped, says Lynn Kimbrough, communications director for the Denver District Attorney's Office. "As the case moved forward, further review of the facts led the prosecutor to the conclusion that we did not a reasonable likelihood of conviction - and once that conclusion was reached we had an ethical obligation to dismiss the case," Kimbrough says.

A search for either the school's or teacher's names does not find any civil filings in state courts, says Rob McCallum, a public information officer for the Colorado Judicial Department.