The Symbiosis of Cognition, Observation, and Interpretation in an Assessment System for BioKIDS Amelia Wenk Gotwals and Nancy Butler Songer The University of Michigan Abstract Assessment is a key topic especially in the high-stakes, standards-driven educational system that is present today. However, many current assessments are not good measures of student understanding because they are based on outdated theories of how students learn and only test fact-based knowledge. In science, with the call for inquiry-based teaching and learning, we need measures that can gather information not just about science content knowledge, but also about inquiry skills and how science content and inquiry skills interact in students’ abilities to reason about complex scientific ideas. This paper examines how an assessment system for the BioKIDS curricular program has been developed based on the three corners of the assessment triangle: cognition, observation, and interpretation. It specifically outlines the theories and beliefs of learning that underpin the system, describes tools created to translate this cognitive framework into tasks that elicit observations of important student knowledge, and uses data to interpret whether the suite of tasks are reliable and predictive of student knowledge. The system provides important information about the BioKIDS assessment system that can inform further iterations of test development and can give credence to the validity and reliability of the test data used to examine student learning. Introduction With the shift in pedagogy and learning toward an inquiry-based method of teaching and learning (National Research Council, 1995), the types of knowledge that are