What would a historian make of our school-graffiti?

My seventh graders carve and scribble all kinds of junk into the desks—names, hearts, dumb jokes, the occasional genuine insult. I got to thinking today: if a future archaeologist found these desks, what would they infer about us? Would they get the culture right, or would they be completely off? Curious if anyone else wonders about the gap between what we leave behind and what actually mattered.