Your class won't even realize they're reviewing author's purpose with this fun, little activity!
My class will first brainstorm ideas on how we could persuade the leprechaun to stay away or what we might suggest the leprechaun could do instead of trashing the classroom! Then, this will be a center that they can complete sometime during the week. I'm planning on leaving candy on their desks one morning with a note to the class saying that they persuaded him to change his ways. They'll eat this up! Plus, no trashing my own classroom!! :)