1. Is having pre-determined understandings developmentally appropriate in the early years? I'm not convinced it is. I'm more for a project with emergent understandings. Lilian Katz in the red version of the Reggio book - Hundred Languages of Children makes a beautiful point, she mentions that the sorts of understandings our youngest learners construct they would come to understand regardless by the time they are 7 years old: just by being alive! It's as if they don't need us to pre-plan any particular understandings at least in science and social studies. Perhaps early years project-based learning should be about the dispositions of inquiry not big predetermined 'central ideas'. If we do predetermine them, then are factual statements developmentally appropriate as Jay McTighe and Grant Wiggins state here?
4. A fundamental challenge we face is that the PYP community doesn't have a common understanding of what a central idea actually is. At one end of the spectrum are those who feel it is a specific understanding (Erickson/UbD bench), on the other end are those who feel it is a broad, open conceptual frame which has scope to be explored but also scope to be interpreted in many different ways. The latter is not an assessable understanding in the UbD sense. Both approaches are very different so surely they can't both be right. Perhaps the latter is more suited in the younger years fitting what I highlighted in point 1.
There also needs to be less emphasis on the POI as the sole centre for integration and more emphasis on authentic links between logical subjects which share the same concept e.g. between maths and the arts (e.g. pattern, shape), between the arts and other arts (e.g. pattern, tone, message) between the arts and language (e.g. audience, message, persuasion) and between languages (e.g. character, narrative, structure).
I would love to hear what others think! Go on, leave a comment! :)