However, conflicting evidence is offered by the one major rigorous evaluation on class size-the experimental study of class size in Tennessee's Project STAR (Mostellar, 1995). Tennessee's Project Star was an experimental study of class size that began in 1985 and lasted for four years. 11,600 elementary school students were assigned to classrooms of differing sizes from when they entered Kindergarten through the end of the third grade. The target size for small classes, to which the treatment group was assigned, was 13-17 students, and control group students were assigned to a regular size class of 22-25 students. This study finds that children in smaller classes in elementary school grades K-3 outperform control group students in larger classes during that time period. These positive reading and math test performance results, so far, have been found to last through the 7th grade. The Lasting Benefits Study (LBS) found that 6th graders had higher test scores with .08 to .16. of a standard deviation on test scores. Among 7th graders, students who were placed in smaller classes retained their achievement advantage, with .14 to .26 of a standard deviation on test scores.