She used floppies I once bought her - since I wasn't aware then thatthe Mac can read/write PC formatted floppies, I was careful getting floppies which were "preformatted for the Mac" (whatever that may mean...)
something ain't true in your statements, beacasue if they are truly mac formatted then there is no way your PC can read them without extra add on software drivers from a third party. End of story.
More likey what happened was she formatted them as 1.44 ms dos disks on the mac.