Karplus’ new passion coincided, serendipitously, with the post-Sputnik wave of efforts to upgrade US science education. Beginning in the late 50s, many other scientists also devoted themselves to science education and the schools, but Karplus was from the start a leader at the elementary level. Initially there was substantial reluctance at the National Science Foundation (NSF) to fund science curriculum projects at the elementary level, but this was overcome in 1959, when Karplus and three colleagues received the first of many NSF grants for the improvement of science content at the elementary level. This work evolved into a monumental 15-year effort called the Science Curriculum Improvement Study (SCIS). Under the direction of Karplus and Herbert D. Thier, SCIS became a comprehensive, fully tested, hands-on, laboratory-based program in both physical and biological science for grades K-6.