A second-grade teacher in Hopkinton, New Hampshire, who has been using a radio contest to teach her students about math and geography got a big surprise Friday.Joan Follansbee has been using WZID's "Pick Your Purse" giveaway to show students how to calculate chances of winning and where the winners live.The Harold Martin School contacted the radio station and explained what the teacher was doing.Marga Bessette and Neal White of WZID dropped in on Follansbee's class Friday and presented her with her own designer purse.Follansbee said the contest has been a fun teaching tool."We started with multiplication because we knew there were four weeks and five chances a day for five days a week, so how many chances total?" Follansbee said. "And we would subtract every time they didn't pull my name, so we'd know how many chances were left."Follansbee also received some flowers.The office manager who told the radio station about the special teaching lesson was also presented with a purse.