[la_senorita_azul]

I think there is no reason why a girl so young should wear a thong. Thongs are for people who don't want panty lines or anything, and hell, you're only young once, live your life and don't worry about dumb things like panty lines.
But I have heard that some girls put them under their leotards for dance and gymnastics so they don't show. That at least makes sense, kinda.