What a prejudice

One of my favorite lectures from my teacher was:
For the first laboratory work on electronics, he collected purely "girl" groups and instead of soldering gave them nail cuts. Regardless of how quickly they determined it – at the next lecture he spent 15 minutes enthusiastically telling how “Ivanov and Petrov in turn half the laboratory tried to melt the nail. Why did you choose this specialty?”

A "child’s groups" did not try to cut nails out? or in boys from birth built-in determiner of nail cuts from the solder.