Background: Free-choice learning, which often takes place in settings such as zoos, is where the learner has autonomy to choose what, where, how, and with whom to learn. Currently, little is known about the potential of free-choice learning experiences at informal settings to engage undergraduates in biology. Purpose: We sought to explore how participation in structured versus free-choice learning experiences and a student's status in their program relate to their motivation, interest, and self-regulation to learn biology after a zoo trip. Methodology/Approach: Students in both introductory and advanced biology courses were assigned to either a structured or free-choice learning group during a zoo visit. Participating students completed a set of surveys before and after the zoo trip to gauge their incoming self-regulation and changes in motivation and interest to learn biology. Findings/Conclusions: We found that advanced students reported higher intrinsic motivation to learn biology than introductory students. In addition, grade motivation decreased and self-efficacy increased after the zoo trip across all students. Implications: Ultimately, there may be numerous ways for instructors to make visits to the zoo and other informal settings more meaningful for undergraduates. Both structured and autonomous learning experiences offer benefits for students across program levels.