This report describes initial findings from a study conducted across three California school districts during the 2021-22 school year of science curriculum materials that were designed to promote learning as called for by the Next Generation Science Standards (NGSS). The study, led by WestEd, was an independent randomized controlled trial to evaluate the efficacy of the NGSS-designed Amplify Science 1st grade curriculum. The curriculum aims to support science language and literacy in day-to-day science lessons in ways meant to integrate science learning with students' literacy development. It is among the first randomized controlled trials of widely available curriculum materials for the NGSS in K-3 classrooms. Of high interest was studying the extent to which the curriculum supports young students' three-dimensional learning, their literacy learning related to reading and the use of science-related language, and the nature of teachers' implementation. The results show that science curriculum materials that use the high-leverage strategy of integrated science and literacy can improve students' proficiency with science, enrich their science vocabulary knowledge and usage, and simultaneously develop their reading skills. [This study was conducted in partnership with LFC Research.]