In this quasi-experimental study, we examined STEMscopes program impacts on science achievement in Longhorn ISD. The report specifically analyzed STEMscopes impacts on STAAR and MAP Growth scores. The present study used a school-level quasi-experimental design, where 8 STEMscopes schools were selected for inclusion and 8 comparison schools (using other curriculums) were chosen for inclusion prior to data collection, based on their similarity in prior achievement and student demographics. The study followed both groups during the 2023-24 school year. The present study was situated in Longhorn ISD, a large school district in Texas, and one of the largest school districts in the United States. The analytic sample consisted of 990 Grade 5 students, taught by 42 teachers across 16 elementary schools. Data sources included Texas STAAR and MAP Growth science scores. Curriculum usage variables included the number of scopes (curriculum units) used at each treatment school. Impact analyses using OLS regression showed statistically significant positive impacts of STEMscopes on STAAR science scores. Treatment students outscored comparison students by approximately 94 points. Subgroup analyses did not show that the impacts of STEMscopes varied by student subgroups. Analyses of STEMscopes usage showed that median unique scope usage was significantly positively associated with STAAR science achievement scores.