Divide the class into even rows.
The last member of each row (at the back of the class) is taken out of the classroom. A “key” letter, word or sentence (depending on level) is given.
The students run back inside, and whisper the “key” to the next student in their row. It is whispered down through the row until the last member writes it on the board.
The first student to write it correctly on the blackboard is the winner!