Some students will gladly jump at the opportunity to make amends by doing ``extra credit" to make up for a low score on a lab or exam. I had quite a few students that were in this situation. Usually, I would come up with an extra credit problem that would be based on something they did well on but add a group of things they did not do well on. The idea was to have them show me that they have learned what they did not get the first time. Completing such an ``extra credit" seemd to benefit both the student's morale as well as their learning. By filling in the gaps of their learning, they are able to move on to more advanced material more effectively. In addition the illusion of ``extra credit" migth give them the false sense that they are exploiting a loophole. Or understanding that they have learned what they failed to learn before might give them more of a faith in the class working to serve them as a ``customer".