In the “you don’t really know until you try it” department, the self-described D.C. mom/policy wonk behind Half Changed World is conducting an experiment to see if she can stay under the U.S. Department of Agriculture’s Thrifty Food Plan for a family of four for a month. Her experiment arises from discussions related to hunger, obesity, and poverty, and seems to be a good way to experience first-hand how poor families have to make choices…