It does seem like it can be approached as a “choose your own adventure” kind of progression. At first, I too thought I would want the entire thing mapped out. I then realized I would likely scrap it midway and to do that wouldn’t be beneficial.
But if I follow Bernie’s advice above and “just start,” and get our feet wet, I think that would be more productive.
For example, we might start the A/B1 for the sake of starting, and after that discussion, we could say hmm…do we choose to dig into solids, liquids and gasses, or maybe we want to talk about living, natural non-living, human things and see the connections that follow?
Or, we might be in one thread and wanting to move through it for a few lessons.
I do like the thought of following the natural flow of a child’s interests!