It could happen in any classroom, it would pass as one of many incidents in a story of school days--but Arthur's discomfiture as the recipient of teasingly unsigned valentines doesn't stand alone very well as a picture-book story. Arthur's ""secret admirer,"" he speculates, ""might be Fern"" (pictured sweet and yearning--and never seen again). ""It could be Buster playing a joke."" But it's obviously either big-tease Francine or come-hither Sue Ellen. Poor Arthur, misled, puts a signed valentine in Sue Ellen's box; then, to his mortification, he drops the unsigned missives (""Arthur and his girl friend sitting in a tree,"" the others chortle) and hears Sue Ellen titter on opening his. But Francine's elaborate, not unaffectionate scheme backfires too: her last missive lures him to the movie theater where Arthur, instead of kissing her, leaves behind on the seat a scattering of chocolate kisses. It's all very plotty, however compressed, and predicated on third- or fourth-grade relationships, situations, and in-jokes that have no younger equivalents--unlike the universal dilemmas projected in Arthur's Nose and Arthur's Eyes. Brown is better than most at projecting whatever's on the mind of his animal school kids, but there remains an inconsistency between the format and the content.