Ambulances rushed to Lincoln Park High School shortly before noon Monday.
"The children were doing an experiment utilizing methanol in a small container and the container broke while it was ignited and some of the burning liquid spilled on top of a work table. A teacher saw it and immediately extinguished the fire with a water-based extinguisher," said Assistant Deputy Commissioner Mark Nielsen, Chicago Fire Department.
A 16-year-old girl who was wearing eye protection suffered second-degree burns to her forehead and stomach.
Four other students suffered minor burns.