Can someone tell where the document came from?

[magicmac]

So I am in a computer class in high school with my friend he has the work all done and i have all his files. My teacher told us she could find out if you copied from another student. I was wondering if shes lieing or not if she isnt is there any way around it?



p.s copy n paste to a new document ruins it( alot of work to fix formatting ect)