Single-district online learning programs were the fastest-growing sector of virtual learning in the U.S. in 2011. Whether it is to provide more options for students, keep more students from seeking virtual learning options outside the school district, or simply to move toward 21st-century teaching and learning, many districts are launching and sustaining their own virtual learning programs. As districts move in this direction, they are taking a harder look at how they will evaluate their local models of virtual education, which is gaining popularity even though reviews on its effectiveness compared with that of more traditional approaches are still mixed. As districts without virtual learning options lose students to online programs, they also lose per-pupil enrollment aid, siphoning dollars from district budgets.