A quantitative case study at a three-section Midwestern elementary school examined a current flexible grouping method, with increased numbers of teachers, being implemented in sixth grade classrooms versus the traditional whole group instruction. Using Iowa Test of Basic Skills (ITBS) data, the research analyzed if flexible grouping can significantly increase reading achievement in sixth grade students. The research compared the means of sixth grade students national percentile rank (NPR) of the participating students in the area of reading, on their fifth grade ITBS test to their NPR on their sixth grade ITBS test. Results suggest there was no significant growth in the area of reading achievement when students were instructed using flexible grouping.