? Question of the Day ?

My question for today is how do you run your centers and guided reading groups? I have a routine in effect but I am always open for suggestions to make improvements. I always seem to run out of time for my guided reading groups which are only 15 minutes long. I just get into doing an activity and then time is up. Some days it gets so frustrating. I try to make the best of my time and start a book on Monday with my groups and we work through that book throughout the week. While I am with my groups, I have 4 other centers going. It usually keeps them pretty engaged and busy but other days not so much. I try to keep my centers interesting so they do not get bored or finish to fast. I am always open for suggestions on how other teachers manage centers, so if you would like to post anything, please let me know.