The five-year project, "Smithsonian Science for North and South Carolina Classrooms" (hereafter "Smithsonian Science"), offers important evidence on the impact of the phenomena-driven science curriculum, "Smithsonian Science for the Classroom," paired with ongoing, differentiated, high-quality professional learning (HQPL) on elementary school student achievement in science, math, and reading. The Center for Research in Educational Policy at the University of Memphis conducted a school-level randomized controlled trial following a cohort of students from grades 3 to 5 using "Smithsonian Science for the Classroom" science and engineering curriculum modules at rural schools in North and South Carolina. Given that the project took place between 2019 and 2024 against the backdrop of the COVID-19 pandemic, these results are particularly noteworthy when seeking best practices for combating learning loss and teacher burnout in COVID recovery efforts. [Additional funding was contributed South Carolina's Coalition for Mathematics & Science.]