Liar, liar pants on fire

Advisory teacher calls me and asks if so-and-so came in and paid for his lost book this morning.
No, I have seen no money from anyone today.
Short time later kid comes to library. I ask him if he has a pass. He says, "No, I have this." It is a folded up overdue notice. I say do you have an ID? He says no. I ask, "Did Mrs. so-and-so send you here?" "Yes."
Me: "Why did you tell Mrs. so-and-so you paid for your book this morning when you didn't?" Kid: " I gave the money to another kid who was coming to return a book."
Me:"You gave your money to some other kid?"
Kid: "Yeah."
Me: "Who is this other kid?"
Kid: "I don't know."
Me: "You gave your money to some other kid and you don't know his name?"
Kid:" Yeah."
Me: "No, really. Who is the kid? I'll call him in here and get your money."
Kid: " I don't know who he is."
Me: "You gave 8 dollars before school this morning to some other kid who you don't even know?"
Kid: "No, not this morning. In my third hour class."
Me: "What class do you have third hour?"
Kid: "Math."
Me: " And who is the teacher?"
Kid: "Mr. so-and so."
Me:" You gave 8 dollars to a kid in your math class and you don't know his name?"
Kid: "Yeah, he was coming to return a book."
Me: " We don't usually get kids in here from math to return a book."
Me: "Who is the kid? I'll get him in here."
Kid: " I don't know his name, but he's in my 5th hour too. I'll talk to him then."
Me: "He's in your third hour and your fifth hour and you don't even know his name and you gave him 8 dollars?"
Kid: "I think it starts with M."
Me: "I don't believe you. I don't believe you would give 8 dollars to some kid you don't even know. When you do have 8 dollars, you come in here with it yourself and pay for your book yourself."

I call Mrs. so-and-so back to see if she would like to hear the story he gave me. She tells me the story he gave her was that he couldn't pay for it this morning because he didn't have his ID. I said, "Oh no, he can pay for a book without his ID. I will figure out who he is."

So, first he paid for the book, then he couldn't pay for the book because he didn't have his ID, then he gave the money to some other kid he doesn't even know to come and pay for his book for him. I wonder what story he will have the next time.

I feel like going into his math class tomorrow and telling the whole class he said he gave 8 dollars to someone in here who was going to return their book and then asking, "Which one of you is it?" We could make it into a math lesson. Draw a Venn diagram of the students in this class and also in so-and-so's fifth hour class. Now, of these students, which one returned a book to the library during this class yesterday? And of this set of students, which one, whose name may or may not start with an M, has his 8 dollars? Oh, none of you? Fancy that. { } Empty set.