Research shows that adolescents enter a circadian-phase delay as they approach and enter high school. On or about age 14, teens become less of a morning learner due to biological factors. Researchers have determined consequences to the adolescent's circadian shift as related to learning; therefore, morning time may have a negative influence on the cognitive functioning of teens resulting in lower test scores. This study was an attempt to determine if time of day, gender, and learning preference using the Morningness/Eveningness Scale for Children (MESC) as proposed by Carskadon, Vieira, and Acebo (1993) would result in a statistical difference in test scores. Cronbach's Alpha reflected a 0.75 internal consistency of reliability of this instrument. The sample was 162 students from a local high school's technology classes between the ages of 14 and 19. An analysis of differences between morning and afternoon classes regardless of gender showed a statistically significant difference. A surprise finding from four groups--morning learners in morning classes, morning learners in afternoon classes, afternoon learners in morning classes, and afternoon learners in afternoon classes--noted that the three groups with an afternoon component in their learning outscored the one group with no afternoon influence in their learning--morning students with a morning learning preference. [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/en-US/products/dissertations/individuals.shtml.]