Just a quick example for PBL that generates vigorous discussions among students:
Form three groups. Two of the groups debate and the third group mediates. Beginning students are often uncomfortable disagreeing with each other so you might want to begin with a controversial but low-stakes proposition. “E-cigarettes should be banned on campus & in classrooms.” The mediators should work to find common ground and propose compromises.
While it’s under discussion, add new details to which students must respond. e.g. how about banning chewing tobacco as well? The goal here is for students to react to changing, fluid situations. The learning will be enhanced if this activity concludes with a debrief where students must analyze and discuss group reactions to the changes.
(A follow-up discussion is for students to formulate how to get buy-ins from peers & administrators to support their decision.)