Reading Groups today

Today was a good day. I think the difference is that I had one group out of the room with another teacher who comes to work with my more advanced group. Then, with clear expectations for behaviour, the other children were able to work quietly. It also made a difference that the first group I had today were much quieter than last week. I think that's because I had kicked some kids out last time for being too noisy. They didn't want that again. So we did a lesson which the kids enjoyed. This group 3 seems to be getting the most out of this time. Maybe it's because their growth right now is the most noticeable. They are successful every time...every one of them. Group 4, the lowest group, seems the most disjointed. I think that's because there's one boy in there that just doesn't get it. He can't even read "a" or "I". I think he's going to be keeping the other kids back. So what do I do? Do I keep going and moving on, or do I slow it down so maybe, just maybe, he'll eventually get it? But isn't that detrimental to the other kids? I already had a parent from the group wonder how come her boy is coming home with books this low again.
I had one boy in my group 2 who hadn't done any of the reading work I had expected the group would do, so when they came to report to me and spend a few minutes working with me at the end of our time today, he had nothing to show. What should I do? I reprimanded him, but didn't know what kind of punishment, if any, to hand out.
My advanced group came back one at a time as they finished their work with the other teacher. For the most part, they were able to refocus on another task as they came back.