If you have not heard about Glenna Tabor's Math Rotations and Guided Math framework, you need to check it out! It's the best math workshop model I have ever seen or used. The students work in teams to do purposeful math station games and manipulatives, while the teacher works with a group of students. The teacher can see at least 8 students a day! Go to Glenna Tabor's website for much more info: http://glennatabor.com/
I have also made a Wiki for my staff to share ideas and to learn more about Tabor. Check that out for more resources.