This project leverages results from several collaborators who have conducted research in the development and validation of instruments for assessing learning and cognition in chemistry. The project seeks to multiply both the efficacy and impact of these instruments by developing, implementing, and studying multiple instrument measures of student learning. The project uses the collective expertise of the collaborators to build a robust suite of cross-validated assessment instruments and to determine how these items can best provide information to chemistry instructors on the effectiveness of their teaching. By enhancing the ability for educators to make teaching choices based on sound data, from validated instruments for measuring learning, large scale change in the teaching of undergraduate chemistry can transform the educational experience of students in STEM disciplines. The intellectual merit of this project lies along two vectors. First, assessment research and validation of new assessment instruments in chemistry provides important data not only from the perspective of teaching, but also in terms of building the knowledge base of the fundamental processes of cognitive growth in chemistry. In order to learn about knowledge acquisition, better measurement technology must be devised, developed and implemented. Second, using assessment instruments to ascertain the effectiveness of teaching methods provides an area rich in opportunities for discovery. Innovation in the measurement of learning in situations where new teaching methods are used is capable of driving decisions based on data rather than anecdotes and enhances the scholarship of what works in teaching. The multiple-instrument methods used in this project are at the cutting edge of educational measurement in chemistry and therefore open the possibility of novel scholarship related to teaching methodology The broader impacts of this work are tied largely to its potential for improving assessment practice within chemistry. Both the Exams Institute of the American Chemical Society and the ChemEd DL of the National Science Digital Library are involved in this project and have large communities of users, national in scope, so improvements made in assessment based on the findings of this project are expected to translate to widespread usage within chemistry. Because chemistry is a cognitive domain with multiple representations used to understand many phenomena, the improvements of assessment instruments in this field are capable of informing similar instruments in other STEM fields, thus broadening the potential impact of this project beyond chemistry. This project is data-driven, and therefore involves the collection of data that can be useful in developing and improving rigorous models of cognition.