Systems and system models are recognized as a crosscutting concept in the newly released framework for K-12 science education (NRC [National Research Council], 2012). In previous work, I developed a learning progression for systemic reasoning in ecology at the elementary level. The learning progression captured five levels of students' reasoning patterns across four progress variables--dimensions of ecological systemic reasoning. In this study, I used the rank correlation and qualitative examples to investigate the extent to which students used the same level of reasoning across the various progress variables. The results showed a wide range of students' reasoning patterns, some of which used the same level consistently across the four progress variables, while others did not. The results have practical implications for curriculum and instruction. I recommend using specific strategies to teach each progress variable, and providing students with opportunities to reason within and across the progress variables.