National and local data show that many female students lose interest in STEM at an early age, female students that remain interested in STEM show partiality for life sciences. This results in gender stratification in STEM subject areas and is evident in high school enrollments in elective courses. This three-manuscript dissertation investigates potential root causes of this problem and presents a mixed method study designed to see if 9-weeks of design thinking-based STEM lessons can increase 6th-grade female students' attitudes, including confidence, efficacy, and identity, toward STEM and interest in STEM careers. A separate sample quasi experimental design was used to evaluate the impact of pilot lessons on 177 sixth grade students. Data was collected quantitatively by survey and analyzed using Welch t-test and Kruskal-Wallis. Additional qualitative data was obtained through observations and analyzed using thematic coding. The findings showed that more frequent exposure to robotics, coding, and engineering positively impacts female students' attitudes toward STEM, particularly engineering and technology which were the focus of the lessons. However, little impact was noticed in female students' STEM career interest over this short intervention. With increased frequency, duration, and earlier interventions there remains hope for encouraging females to pursue pSTEM courses and careers in the future. This information could be used to help guide elementary school STEM program development currently in progress or in the future which may help to reduce gender stratification in STEM over time. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]