Both physically and socially, this instructor made space in the class to allow for participatory learning, with students, mentor, and professor as participants. They don't discourage questions. They don't discourage involvement. The students can teach the students. They guide you, but don't butt in and say you're not supposed to help other students.
Some instructors appear to be initially reticent about rearranging classroom furniture.
Others have experimented with various arrangements. We observed that the physical set-up of the classroom did indeed have a great effect on student learning and class participation. A class where students are seated at tables or desks feels quite different from a class where students are sitting in a large circle all facing the center. Everyone's facing each other and nobody's in front of anybody. It helps to relax the way that we're all in a circle and no one is at the head of the class, and no one's at the back.