We have preservice teachers from Western Oregon University providing free mentoring in the current FunPoW, Jar of Coins, at http://mathforum.org/funpow/. The problem will be live for one more week.
This is a great opportunity for your students to receive feedback on their problem solving and communication. If your students receive replies from a mentor, please encourage them to revise. Your students will learn more, and so will the mentors!