I just don't believe 100% attention and retention is possible. Far too many of todays students come to us with poor school habits that we cannot easliy rectify in the short time we have them.
In addition, at least in my school, we have far too many students who arent there to really seriously learn at all, and right off the bat, this skews so many of the concepts of all of these courses. Its something none of them address that I have seen
Do the best you can-- but don't obsess over the losses.
