Put the Creature on Trial.
The play raises some interesting questions. For instance, when someone commits a crime, is that person the only one who should be punished? Might other people be responsible too? And if so, is it even possible that the criminal isn’t really at fault?
Have a trial to decide whether Frankenstein’s monster is responsible for the murders he committed. Two students can be lawyers, one can be a judge (to settle disputes), some can act as the jury, and a few can be witnesses (Victor Frankenstein, the creature, Mr. De Lacey, etc.). Once everyone has gone over the facts of the case, each lawyer can explain why the creature should or should not be blamed for his actions and call witnesses to give evidence. Then the jury can decide the creature’s fate. Have fun!