Re: Student ability
Different people learn at different rates, plain and simple. Your fellow might very well be picking up a lot more than you realize, and it will gel at some point quite suddenly. Two times a week though is possibly not enough practice time. Do you offer more classes? You might suggest he practice more, or even simple tenkan and hamni at home (just something to teach his body over and over again). Could he be a student who needs primarily to learn through his body, and to shut off thoughts in his head (explaining, thinking too hard)?
We had a woman at our dojo who practiced for 8 years rather steadily (3-4 times a week), yet every new beginner treated her like a beginner. It had to do with possibly a form of drawfism, where her arms were much shorter than her body. Her movements for the first 4 years or so were quite rough, but towards the end of her practice (she's since quit), I had noticed a huge difference in her ability, and in that she had actually gained quite a center. What I am saying with this is that if you compared her against other folks who were more physically adept, that she might not look particularly able (from an outsiders perspective), but comparing her against herself and where she started, I would say she came along further than anyone else I knew in that time frame. She gained confidence, center and ability, and it worked well for her. My teacher did continually promote her, because he saw this massive progression.
To me, this example really is one of someone learning something more deeply, more to the core, than on the surface would show. Perhaps this will happen with your student as well.
Just my $0.02