Today, we are going to solve a crime. Yesterday afternoon, a man stole a briefcase on the street. You are going to find out who did it and what the person looked like. If you are A, you are the police officer; if you are B, you are the witness. You need to describe the criminal' apperance by asking questions.
If you notice the other ws I uploaded, I have adapted the game to the topic I am teaching recently which is about describing looks.