US undergraduate students who participate in laboratory sections of physics courses show no discernible improvement in their exam scores over students who participate in only the lecture sections. In a study published in Physics Today, authors analysed9 introductory physics-lab sections taught by 7 different instructors and involving nearly 3,000 students at 3 US institutions (N. G. Holmes and C. E. Wieman Phys. Today 71, 38–45; 2018). The researchers compared the midterm and final exam scores of those who took the optional lab component — designed to support student learning of lecture content — with the scores of those who did not. In follow-up interviews, students said that it was important for them to make their own decisions in lab and to reflect on them, but that they were not permitted to do so in structured lab courses. The authors suggest that lab instructors could better emphasize experimentation, decision-making and critical-thinking skills. They say that students could collaborate to design experiments to test their own hypotheses for explaining surprising phenomena.