I am currently working in a school that is interested in using Investigations and starting in a gradual way so that teachers do not feel overwhelmed. We are considering having each teacher do two units at each grade level next school year, with the purpose of creating a common strand up through the grade levels. What we are wrestling with now is which two to start with for this next school year. What in your experience would you suggest in a k-5 school? Several teachers already are fully committed to Investigations and use it exclusively. This is more for the staff that has never used Investigations. I would appreciate any and all suggestions.