class design
I don't know if I can help but I work with K/1 students with mod/severe with a wide variety of skills like your students. I only have 2 paras and a behaviors that feed off each other (but topic is for another day.)
My class is set up on 4 center rotations: Writing center for fine motor skills (cutting, fastening buttons, etc.) & writing anything from letters to numbers to sentences. Another center is Word/Number Study where we literally study words. It's just a chance to use more vocabulary & conversation with the kids. (I have 3 with SLI and 3 with Autism) We have a Guided Reading Center where we work on letter/number identification, sounds, pre-reading skills, syllables etc. I try to use thematic books here to build vocabulary and help them with reading strategies (using visual cues) and retells. We have one center that is purely for fun, the Discovery/Book Center. They do this independently because I don't have an adult to supervise but when I did the para helped teach the kids how to play together and use the toys. It's surprising to me that some of them lack social skills like taking turns. I wanted to have an independent listening center (books on CD or tape) but they couldn't do it by themselves.) We usually rotate around the room twice a day, once for Literacy and once for Math, with 8-10 minutes at each center. The kids are grouped together by similar goals/skills.
I have a schedule for them to carry from center to center. Last year I used colors (blue center, yellow center) then they (district) said I should include words so I did but I like the color system better.
I hope this helps! Good Luck!