Has anyone played around with encouraging (but not requiring) students to teach one another?
One way of demonstrating mastery of the material is teaching it to others. I feel like if student A says "Student B really helped me understand the material" that increases my Bayesian posterior that student B understood the material really well (and also that student A understood it, since presumably after student B explained it, student A understood it at least better than they did before).
I wouldn't do this as the only, or even major, part of their grade, but it seems like if the grade is to reflect learning, that teaching it to others certainly reflects on their learning.
(Additional context: this is for a university-level elective technical course in Comp Sci, for 3rd and 4th-years mostly. I generally do flipped classroom and alternative grading - some combo of ungrading, mastery-based, standards-based, but I'm open to ideas. The class has about 55 students, so whatever it is can take some time but not be *too* time-intensive on me & the one TA.)