Kramer and Filipp evaluated the impact of a weekly in-school chess intervention taking place over the course of four academic years on German students’ cognitive development and behavior. The sample was comprised of elementary school students, with 84 in the treatment group and 83 in the control group. Treatment group students were compared to control group students in a school with similar demographic characteristics and within close proximity of one another. Neither assessment was described in detail. Mean scores on the assessments were compared using tests of statistical significance. The authors found an effect size of 0.673 standard deviation units on the cognitive assessment and an effect size of 0.267 standard deviation on the behavioral assessment. The findings were statistically significant. The study was eligible for inclusion in the systematic literature review and categorized as Tier III since students were not randomly assigned to the treatment or control groups.