One such approach is the design of diagnostic assessments and surveys. While many instructors develop questions to assess student learning, diagnostic research assessments undergo rigorous design, testing, and validation processes to facilitate objective comparisons between students and methods of instruction. These assessments are like detectors that must be carefully crafted and calibrated to ensure we understand what they are measuring.<br>The Cornell Physics Education Research Lab has a large focus on studying and developing learning in lab courses. Researchers are collecting data to evaluate the efficacy of lab courses in achieving various goals, from reinforcing physics concepts to fostering student attitudes and motivation to developing critical thinking and experimentation skills. They are designing innovative teaching methods to harness the affordances of lab courses, namely, working with messy data, getting hands on materials, troubleshooting equipment, and connecting physical models to the real world and data. There are many open research questions related to understanding how students learn these ideas.