  Improving students' understanding of the nature of experimental physics is
often an explicit or implicit goal of undergraduate laboratory physics courses.
However, lab activities in traditional lab courses are typically characterized
by highly structured, guided labs that often do not require or encourage
students to engage authentically in the process of experimental physics.
Alternatively, open-ended laboratory activities can provide a more authentic
learning environment by, for example, allowing students to exercise greater
autonomy in what and how physical phenomena are investigated. Engaging in
authentic practices may be a critical part of improving students' beliefs
around the nature of experimental physics. Here, we investigate the impact of
open-ended activities in undergraduate lab courses on students' epistemologies
and expectations about the nature of experimental physics, as well as their
confidence and affect, as measured by the Colorado Learning Attitudes about
Science Survey for Experimental Physics (E-CLASS). Using a national data set of
student responses to the E-CLASS, we find that the inclusion of some open-ended
lab activities in a lab course correlates with more expert-like postinstruction
responses relative to courses that include only traditional guided lab
activities. This finding holds when examining postinstruction E-CLASS scores
while controlling for the variance associated with preinstruction scores,
course level, student major, and student gender.
