Abstract
While STEM integration and engineering education have become increasingly important, most integration units use physical or earth science topics. Thus, the purpose of this research was to explore students' discussions during two life science-focused, engineering design-based STEM integration units to determine what types of connections within STEM students were making and whether these aligned with the life science learning outcomes of the units. This study employs a qualitative content analysis methodology to categorize the instances of science that students used during engineering design. The results show that students in both STEM integration units used science during engineering design, but how much life science vs. physical science used depended on the criteria given by the engineering challenge. This suggests that when developing life science-focused, engineering design-based integrated STEM units, curriculum developers need to carefully consider whether life science serves only as a context or whether it is required to develop solutions to the engineering challenge.