A lot of learning takes place outside of the classroom. Times and times again, it has been demonstrated that peer teaching is one of the most effective way to

A lot of learning takes place outside of the classroom. Times and times again, it has been demonstrated that peer teaching is one of the most effective way to enhance learning. In Physics, many profs (myself included) encourage students to discuss problems and help each other but without copying solutions. When you give one assignment every week with 5 to 10 problems to solve, and assignments count for 20% of the final grade, each problem is worth very little... which is why you do not penalize students strongly when you catch them for the first time copying a solution to a problem. Learning the difference between explaining the solution of a problem (similar to explaining an algorithm) and just giving a solution to copy may is not something that is immediately obvious for some.