U.S. schools have witnessed educational reforms that have shifted science curriculum and pedagogy within classrooms. Yet, all these reforms have failed to reduce the racial and gender gaps in STEM fields. In 2016, New York State implemented the New York State Science Learning Standards (NYSSLS) to address these gaps. Problems remain, however, with the NYSSLS standards. The NYSSLS do not offer teachers pedagogical practices with regards to implementation. Students are expected to engage in practices as they emulate scientists, without any direction for teachers to support students through these practices, and they exemplify a deficit mindset by placing the blame of content accessibility on racially and academically marginalized students. The rationale for this qualitative action research study was to address the gaps identified in the research and the problems in the NYSSLS through the addition of universal design for learning and culturally responsive teaching. The data for this study included three cycles of action research, interviews, and field observations with seven fourth-grade teachers from two school districts who participated in professional development (PD) sessions prior to implementing a STEM lesson. Findings from this study indicated that when teachers are supported with PD sessions that offer hands-on training through the eyes of the students, vicarious experiences while working with their colleagues on lesson planning, and support with coaching during lesson implementation, the identified barriers to learning are minimized. Such experiences were found to increase teachers' self-efficacy in supporting students through STEM lessons and diminish deficit mindsets about certain students, although there was also evidence that suggested oppressive normativity was a problem in a special education classroom. Additionally, it was found that as teachers gain self-efficacy in teaching STEM lessons, they let go of their authoritative power by allowing students to collaborate and take control over their learning. Barriers to learning are then diminished as students become empowered to access the content in the NYSSLS, problem-solve, and successfully navigate the practices. [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.]