A group of seniors at Spence, the Upper East Side girls’ school, is aiming to disrupt the June 14 commencement by refusing to wear the required graduation garb: a below-the-knee white dress (and no visible bra straps). Instead, the girls will wear white pantsuits in protest. “It’s not a finishing school anymore, it’s a college-prep school that has strong academics, so do we really need to wear dresses?” asks Cordelia Chansler, Spence ’05 (other alumnae include Gwyneth Paltrow, Jade Jagger, and Mike Bloomberg’s girls). But most alums are less than incensed by the dress policy. “I think it’s nice to have everyone look uniform,” says one recent graduate. “Sorry, but nowadays, left to their own devices, the girls would look like sluts.” And even Chansler doesn’t regret going along in the end. “I’m glad that I went through with it and wore a dress. I think these girls will be sad they wore pants afterward, but, whatever, they’re 18,” says the 19-year-old. Spence had no comment on the looming controversy. Next: Zombie Version of Manhattan Surprisingly Inaccurate