I think you are doing a great thing for the school. As a retired teacher, one of the best things about these projects is that they are not perfect - just like all the beautiful little hands and voices that made them. I would suggest that you put them together as you got them - flaws and all as the outside binding will hide all of those imperfections. It will be treasured as something that the children made which is the point.
Hope that put a different perspective on this. Good luck - it is beautiful and will be treasured by all the eyes that gaze upon it.
Jana