Well, we did meet in the Coffee Box. But beyond that, there was a history of exploring reasoning with boxes.
So, three constraints to give a direction.
Right Lines: Conservation lawsConservation laws are a special way of thinking about the
may-be's. Of the six conservation laws in physics, we chose to explore mass and energy separately (thinking of current pre-19 practice in schools) and momentum because it is a vector. Angular momentum did not make the cut because it is not widely exploited, and we did not thinking reasoning with boxes had much to say for the conservation of charge, lepton number or baryon number. So, here follows an exploration of reasoning with boxes about:
We're after exploring boxes as tools for thinking with
The boxes contribute to the quantity to be compared across
may-be's, allowing insight into the way that the value of the quantities can be altered. But comparing the boxes directly across
may-be's is not, in our experience, as a result of considering a number of examples, fruitful.