Your points are well taken. The data which should drive decisions should include the pd data, implementation data - use of materials, lesson design and delivery, classroom culture, etc., as well as, the data which reflects the impact of all of this on children. That data can include student work in the form of science notebooks, performance tasks embedded within and/or at the end of the unit, tests - criterion referenced and/or norm referenced. To ingnore the impact on students is a major flaw from a sustainability perspective.