this idea will make a million dollars. [edit: make sure you hire Lisa Frank to design them]
god, what a nostalgia bomb. I had one just for the 6th grade. It was ugly. even as an eleven-year-old, i thought it was ugly, but it was in the sale bin with all the other design abominations nobody else wanted, so my mom would buy it at that price. it also didn't describe me very well since I hadn't made the jump from Nickelodeon to MTV at that point. despite mine's looks, the utility of them appealed to me, and it was something popular at my school during the short period in my life when popular stuff seemed desperately important to me. i managed to destroy it pretty quickly due to my MO of being harsh on all my gear and switched to normal pocket folders
i couldn't actually remember what mine looked like other than it was ugly and purple, so I googled "purple trapper keeper" and sure enough, second image result. the internet is insane.