From the abstract: "Groups of five to seven students were assigned learning activities as treatments in a Latin Square design consisting of three experimental periods."

Erickson, M., Marks, D., & Karcher, E. Characterizing student engagement with hands-on, problem-based, and lecture activities in an introductory college course. Teaching and Learning Inquiry. https://journalhosting.ucalgary.ca/index.php/TLI/article/view/67809