This article describes a method of flexible redistricting for K-12 public school districts that allows students from the same geographical region to be bused to different schools, with the goal of meeting average class size (ACS) target ranges. Results of a case study on a geographically large school district comparing this method to a traditional one-region-to-one-school redistricting method are given. In this case, the flexible method did significantly better at meeting the ACS target ranges, while at the same time reducing the number of classroom teachers. Although this method is presented as a way to better meet ACS target ranges, it could also be used to help districts meet other goals--racial balance, socio-economic balance, or anticipated growth for which redistricting is typically used.