Summer School

In my summer school class I have numerous English Language Learners who are taking the class for something otherthan, or in addition to, earning a lost credit. I commend these students, some who have very little English skills, for their desire to improve skills while immersed in an English speaking classroom.
The great difficulty I have though, is that I am not equipped, in my own teaching skills, to provide for the needs that they have. Language has already shown itself to be a great barrier in the communication of directions and lessons. While during the normal school year, ELL students have the appropriately educated people around the school to facilitate their learning, I do not have that available during the summer session.
I am charged with the task of not only communicating through the language barrier, but also evaluating each student's progress. As I sat with one student today, it was obvious that he was frustrated in his inability to communicate with me, and I was at a loss for ways to communicate with him. He finally looked at his watch and said he needed to catch a bus. I felt the same way. There is a sense of powerlessness that controls the tongue when one does not have the words needed. But here is what I did understand. My student didn't understand the book he is supposed to be reading. He didn't understand the directions for the assignment that went with it. Here is what I think about all of this.
How in the name of NCLB am I going to evaluate this student? He has asked for a Pass/Fail grade. But how do I know whether he is passing or not? How do I accomodate during a summer session without knowing what and where to accomodate?