Fairness?

So I've been grappling with the issue of fairness for a few weeks now. My 6th period class is a very mixed bag in terms of students' skill levels, which makes sense when you work in a full-inclusion school with no tracking whatsoever. I have a few students who rarely need any explanations from me and do all the work ridiculously quickly, and I can never give them enough challenging work. On the other hand, I have several students who need serious one-on-one tutoring and who cannot possibly follow along during class. It can create quite a frustrating atmosphere for both me and the students.

I'll be honest, I haven't really been worrying too much about the students who are doing well. Part of me feels bad that I'm not taking enough time to make sure I challenge them, but I'm really just much more worried about my students who have no clue as to what's going on. Since I have this group of students whose grades range from 30-60%, I've been trying to find anything to motivate them to do their work. So one of my ideas is to give them significantly smaller assignments so they can feel better about at least accomplishing something. While I usually think this choice is justified, sometimes I feel weird knowing that I expect someone students to complete all the work for a perfect score and other students only have to complete some of it for a perfect score. I know it's definitely not equal, but is it fair?

Let me give you a summary of a couple of those students that I'm targeting with this plan.

I have one student who sits in the back of class every day and does barely any work. He usually doesn't even take out his assignments or even a pencil during class. So I've asked him a couple of times about why he doesn't do anything during class. He told me honestly that he was just lazy, which I appreciated, but I also wanted to change that. So I first wanted to know if he understood the material, so I asked him how to do the first problem on one of the assignments, and he explained it perfectly! So I said, "Write that down," and he said, "I don't want to." I said, "Excuse me?" He said, "I have a lot of trouble writing things down." So in order to get him to do his work, I've started asking him to at least complete the first page of the assignment. I figure something is better than nothing, right? But is that fair?

I have another student is actually extremely motivated to learn the math and not at all by his grade. However, on a daily basis, he goes through this frustration cycle that can sometimes be impossible to break through. Every single day, he gets really frustrated and angry with new material, and he always claims, "I don't get it. I don't want to do it. I can't do it." And he totally shuts down until he gets one-on-one help (which is hard to give to him every day with such a big and diverse class). And as soon as he gets 10 minutes of help, he gets excited and says, "Oh, I get it. I can do this. That's easy." And it baffles my mind every single day how he goes through this roller coaster of emotions in every single class. So again, I've been giving him smaller assignments because I simply want him to be able to stay on top of his work when he can't get individual tutoring sessions with me. So is that fair?

I have other students in other situations, and I'm trying to make different accommodations and modifications for each student. However, sometimes it's really difficult for me to keep track of, and I'm still so conflicted about fairness. I just desperately want my students to learn, and even as I give them all these accommodations, it doesn't seem to help all that much. Their grades go from a D+ to a C-, and they feel successful for about a day before they fail the next quiz. Anyway, I'm just so frustrated, I would love to hear any suggestions or thoughts!