Way too sexy for school, though you might be able to pull it off for prom.
I think that is an adorable dress, but I can't imagine where one would wear it. It simply screams, "Rip this dress of my body and take me now!"
If I were still in school, I would definitely wear a vintage shirtwaister to school. I do wear vintage shirt-waist dresses to my day job on occasion, and while I may have to endure Lucy Ricardo and June Cleaver wisecracks from my co-workers, it is not an inappropriate look for daywear. A 1950s suit would be cute for school, too, especially one of the ones with a boxy little waist-length jacket with 3/4 sleeves and a very full, wide, pleated skirt (with a petticoat under, naturally!)