Exact same thing happened at my highschool, scene of the crime was a very muddy ditch. I wonder how many chemistry teachers the world over have made that exact same mistake.
I'm beginning to think I was lucky to have the chemistry teachers that I had. I recall my main chem teacher saying that we students could not do this experiment ourselves as we'd likely blind ourselves. He was very particular in the amount he selected and mentioned it'd go off like a bomb if too much was selected.
BTW, the lab table in our tiered lecture room was nearly 6ft/2m from the first row of seats and for the exercise the teacher had a sheet of perspex in front of the experiment (perhaps it'd happened to him with an earlier lot of students).
BTW, the lab table in our tiered lecture room was nearly 6ft/2m from the first row of seats and for the exercise the teacher had a sheet of perspex in front of the experiment (perhaps it'd happened to him with an earlier lot of students).