Using Peer Feedback to Promote Reflection on Open-Ended Problems
  This paper describes a new approach for learning from homework, called Peer-Assisted Reflection (PAR). PAR involves students using peer feedback to improve their work on open-ended homework problems. Collaborating with peers and revising one's work based on the feedback of others are important aspects of doing and learning physics. While notable exceptions exist, homework and exams are generally individual activities that do not support collaboration and refinement, which misses important opportunities to use assessment for learning. In contrast, PAR provides students with a structure to iteratively engage with challenging, open-ended problems and solicit the input of their peers to improve their work. 
Daniel L. Reinholz and Dimitri R. Dounas-Frazer
physics.ed-ph