Philadelphia's 2,000 corner stores offer convenience, a variety of products and give all parts of the city a neighborhood feel. And for areas where there aren't any grocery stores within walking distance, corner stores play an even bigger role in the lives of many residents. In fact, more than a quarter of Philadelphia students visit corner stores twice a day, five days a week, according to "Snacking in Children: the Role of Urban Corner Stores," published by the Temple University Center for Obesity Research and Education. The study found that just $1 can amount to 350 calories, which may be part of the reason why nearly one in two students living in America's cities are overweight. But a new program is trying to change that. The Center City nonprofit Food Trust teamed up with the city's Get Healthy Philly campaign to teach students to make healthier choices and help corner stores market, stock and sell healthier foods. Currently, the Food Trust is working with 500 of the city's corner stores. To learn more, we checked out a corner store in South Philly.