David. Yes, I’m still uneasy. But I’m not sure it is for the same reason as you. If we just had big statements, then they would, inevitably, be open to interpretation and we would be wanting to define them more tightly (with lots of depends and ifs). So we might end up with the atoms anyway. For example, if you tale Newton’s second law as a big idea, then it breaks down quite a lot. So I think this is where the generalise/specilise arrows come in.
In some sense, I see pillars of a big idea (say [email protected]; or even the concept of force) growing upwards. And, as you ascend a helical route, you pass through points on the towers and build your understanding/conception of that idea.
So, for N2, you can grasp at an early stage that a force will change the motion of something. But you are still a long way from grasping how force affects acceleration. So, big ideas is good. But there is structure within those ideas and the map has to link to that structure rather than to the bubble of the idea.
It may be that we haven’t got the structure quite right rather than we shouldn’t have structure at all.
BTW, it is worth looking at the project 2061 maps. For me, they are *too* general.