Relative age effects are the outcomes that are manifested when older and younger students are compared in an environment such as a classroom. Research has shown that older students have higher student achievement than younger students (Datar, 2006; Lin et al., 2009; Oshima & Domaleski, 2006; Yesil-Dagli, 2006). This case study grouped students by their birthdays to form kindergarten classes where the average range of ages were within a four month span. Focus groups were used to determine the effects of this practice from the teachers’ perspectives. Some teachers thought that grouping kindergarteners by birthday improved teacher-student relationships, allowed for better student instruction and reduced negative student behaviors. However, other teachers felt burdened by groups of the youngest students and lamented not having older students to teach and model for their younger peers. The teachers in this study thought that the youngest students in a cohort were less prepared for school and required more of their time and instruction than the oldest students.