Area and Perimeter Math Stations

I think I may have actually got my math stations up and running.  I bought the Math Stations for Middle Grades book by Laura Candler and her ideas for rotations were so simple yet so helpful! Thank you Laura Candler!  I decided to have three stations: Teacher, file folders, and math tubs.  Each station lasts 15 minutes with an extra five minute added on for housekeeping and switching stations.  Each student has a folder to store their station checklist and any papers acquired from the stations.  (This sheet can be found in Laura's book.)  My students and I compiled a chart of Math Station Expectations.  For a first time around, they did such a wonderful job!  I really believe they like the stations too.  I'm wondering though if I may have put too many options at the math tub station.  Tomorrow when I have the students rotate through, I am really going to stress the importance of trying all the activities at the tub station.  I may need to eliminate one of my tubs.  Right now I have three there: Pentominoes with area and perimeter, pattern blocks with symmetry, and tangrams with composing and decomposing shapes. Here is a link to my pentomino freebie if you missed it yesterday.  
Do you use stations? If so, leave a comment and tell me about your experience with them.  I love comments!