My system is simple. Each student gets a "centers menu". I designed it so that any child in my classroom with any level of language and cognitive ability could use it. It has a green side and a red side. Simply, the green is "to do" and the red is "all done". Each student has 3 centers each day. On my SMARTboard, I have up a picture that says "centers" and then under that a chime which I ring about every 12-15 minutes. We practiced a lot but my students know now that they stay at their center until the chime rings. When the chime rings, they clean up and move on to the next.
I printed out TONS of little icons for my centers. This way there is no confusion about what the next center is. I pre made all these so I can switch centers all the time without anyone getting bored.
I have kids in and out of my room every two minutes. Since I am a sub separate room my kids are on all different levels. This system has made it so easy for me to have flexible grouping and meet 1:1 with my students each day.
I hope this helps you!
My centers menu- one per student
I keep all the icons in the top drawer ready to go
My (messy) shelf of centers games and activities