Several years ago I attended English courses here in Minsk. Our group was quite good at grammar but we were too shy to use our oral English skills in classroom. Then our teacher invented a special system for us.
A person who said even a word in Russian without teacher’s permission got a Black card. It were just pieces of paper. One side was all black and from the other side she wrote different penalties. Sometimes it was funny… but not for those who got them I think.
And the other part of those