In the years 2005 to 2019, the number of American women receiving a degree in engineering was below 20 percent. Furthermore, even after receiving a degree in engineering, 40% of those girls do not enter the profession. While the above graduation data is essential for understanding the problem at the end of the educational journey, it doesn't point to a girl's reasons to pursue or not pursue a degree in engineering. Nor does it express the societal impact a diverse engineering workforce could have on society. However, not only do we need more engineers, but we need more diversity in how we solve the ever-increasingly complex problems humanity will face. This proposed two-phase study will explore the shifts in high-school girls' engineering identity. Based on past research, my theory of improvement takes a blended approach that incorporates application, collaboration, and empathy-building in engineering design challenges. Phase one will take the form of a project-based unit plan that guides students in creating a solution to a societal problem. By transforming the traditional classroom format and fostering positive classroom interaction between students, the Engineering Design Unit increases a girls' understanding of the assigned problems and how to develop a solution to those problems. Finally, phase two will take the form of an open-ended essay to gather qualitative data on shifts in a girl's engineering identity after completing the Engineering Design Unit. The Engineering Design Unit ran over 30 school days in the fall of the year 2021 with three sections of the Introduction to STEM course and a total of 72 students. However, only data from the twenty-three students who identify as a girl, female, or woman will be analyzed to understand the shifts in high-school girls' engineering identity. [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.]