How do labs impact students' critical thinking skills and experimentation views?*

Instructional labs are fundamental to an undergraduate physics curriculum, but their possible learning goals are vast and with limited evidence to support any particular goal. In this talk, I will describe a study evaluating the efficacy of labs with different goals and structures on students' critical thinking skills and views about experimentation, using an extensive database of survey responses from over 20,000 students at over 100 institutions. We find that labs focused on developing experimentation skills improve students' critical thinking skills and experimentation views compared to labs focused on reinforcing lecture concepts - a pattern that is consistent for all demographic groups. Our analysis also shows that activities to support students' decision-making and communication explain over half and a third of the effect of skills-based labs on students' critical thinking skills and experimentation views, respectively, while modeling activities have only a small effect on performance.