Motivation, Attention Span, and Intelligence

My cooperating teacher, TA, and I are seeing some major changes in a few of our students. As we are getting to know the students better, we are better able to help them. One of the students in particular has a hard time concentrating. We have found that by giving him the motivation of getting a sticker for the completion of each major assignment of the day, he is better able to focus. Being able to focus has made a big difference in the quality of his work. Another student also has trouble concentrating. We have not been able to find an effective motivational strategy for him yet.
There are also a few students in our class that do not listen, so they never know what is going on. For one of them we have found that physical proximity makes a difference. Another student needs the instructions explained one on one; he has trouble processing information given in group settings. As we have made these modifications, it is amazing the change in the work coming from these students. Some of the students that we originally thought were behind are actually highly intelligent and just needed some minor accommodations. I truly think that this class is one of the most intelligent classes of second graders that I have ever come across and it makes me sad that I will soon be leaving these students for my next placement.