Last year, I did real world matrices done in stations/posters/gallery walk style. I said that my only change would be to give the kids a "passport" of some sort so that they had more responsibility in solving the problems. Thankfully, I remembered that this year so the groups that were finishing early received their passport early, thus keeping them entertained. But of course, there were always the select few who's engagement was not present.
I really love doing this activity because it never fails for kids to show me a way that I hadn't thought of and yet again, it happened, from one of my recovery kids. It was amazing and awesome.
We have dry erase desks, the kids love them. They nearly get covered every day with kids doing their daily check for understandings. They're also great when I want to explain something to one kid so I'm not writing on their homework how to do a problem.
Always encourage the kids to explain/justify their method. It's a really good practice, especially with Common Core.