why do you lie?

do you think I'm stupid? I'm not.

Everything my students do goes in their portfolios. Big ol' folders. They know this. I marked my grade 9 portfolios and found that some were missing a lot of stuff, so I told them they need to get their stuff in there so I can mark it. Fine. A few days later, yesterday, one of the girls missing stuff in her folder comes up to me and asks if I got her project. I said no, I didn't check your folder again, is it there? No, she says, I put it on your desk. Now, my desk is not the tidiest thing, but it's in pretty good shape, not very cluttered, and I know what's there and what's not. Her project was not. I said, well, I don't know what to tell you, unless someone came along and swiped it immediately after you put it down, then it has very mysteriously gone missing. I have not seen it. And you know you put everything in your folders, I have been stressing that since day one. She said well what do you want me to do, redo it? I said well it's awfully hard for me to mark something I haven't seen! I left it at that.

Today, I walk by her table, and she's working on this same project. I say hey, you found your project. Interesting. She said oh no, I redid it. I took a piece of paper yesterday and redid it last night. I said really? With the same picture as before? That you said was too difficult and regretted choosing? That's sort of odd, isn't it? She didn't really have an answer for me. I didn't push it, but I will talk to her tomorrow, because the more I think about it the more angry I get that she blatantly lied to me. I just want to let her know that it's very clear she's lying; she wouldn't have chosen that picture again given a choice, and there was no paper out for her to take. So even if she's telling the truth, she got paper from somewhere she wasn't supposed to be. rrg. I assume what she was hoping for was that I would feel so bad for having supposedly lost her project that I would just let it go. But I know I didn't ever have her project, so I'm not going to fall into that trap. Anyway, so then it's easier for her to finish the one she started than do a whole new one. I'm really bitter! I can't outright PROVE that she's lying, but she is, so what do I do?

Teachers of the blogging world, please advise!