I too have used the 5th grade investigations with new teachers teaching inner city kids who are seeing project based hands on math units for the first time. I started using the level 5 books and had some success but it was slow. The students had never been taught to think. I rethought my lessons and decided to try using the level 4 books which are also appropriate for fifth graders. MUCH BETTER! Tell your teachers to hang on and have faith. The methods we've been using in the past definitely don't work as evidenced by our dismal performance during the TIMSS testing and our students' math achievement nationwide is in a dismal state. We have to have reform in our mathematics instruction! This curriculum isn't perfect, but far surpasses our traditional text book page by page instruction.We teach a little bit of a lot of things but no one really learns anything in depth. We've got to engage our children in lessons that build a foundsation for deep understanding not rote memory of isolated skills. Good luck, hang in there and I feel certain you and your teachers will begin to experience success. When you find areas of the curriculum such as buliding place value understanding in the 1st 2nd curriculum, supplement and then spread the word so we can use your good ideas.