This was a quasi-experimental study that compared three different lesson closure methods used in a middle school mathematics classroom over a period of seven weeks. This study used a repeated measure methodology to gather data over time from 106 middle school student participants. Lesson closure methods were randomly assigned over the 30 instructional days and participants were assessed the following day. Assessment scores were compared using analysis of variance at the p less than 0.05 confidence level. The findings of the study resulted in a significant difference (p = 0.001) between three types of lesson closure methods studied. The results indicate that teachers who utilize the instructional method of lesson closure result in higher student assessment scores on posttests. The three methods studied were lesson closure, teacher closure, and non-closure as defined in the study. While the findings are significant, further research is recommended regarding applicability to other secondary content areas such as English or the social sciences as well as applicability to elementary classes. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]