Recent reports have begun to lay the foundation for a re-visioned K-8 science curriculum which includes four strands that could be used to define and assess science proficiency for all students. Using these strands as an analytic lens, this pre-post multiple-case case study explores elementary school science teachers' practices and their students' actions. This work focuses on naturally occurring ordinary events and builds a description of how these strands of proficiencies are being developed. The results of cross-case analyses suggest that while the participating teachers do engage their students in activities and exercises that contribute to the development of all 4 strands of science proficiency; the nature, duration, and distribution (across the 4 strands) of these activities varied.