If the initial premise is that differentiated, mastery-based education is an ideal, then what does the ideal classroom look like that meets that need?

How is adequate differentiated instruction going to take place?

I think "flipped" is a bit trite and over-extended into its own definition. Setting that aside, it isn't at all clear how you get to mastery-based without looking a bit flipped?

I've wondered this a lot. Even reflecting on my childhood, or looking at my son and his math interests. It is really hard to see the fair balance in the mix. If you have 20 kids each working at a different pace on different material, in an hour do you give each 3 minutes of direct instruction at their level?

That's a cluster with N=1. What if in the class of twenty your cluster size averages 4? But there are 8 clusters: 4 clusters of 4 and 4 clusters of 1. Do you divide the hour by 8 or by 5? Do some kids get 12 minutes of instruction at their level because they are in a cluster of four and some get 3 miutes? Or is it 7.5 minutes per cluster?

What if you take "home" out of the equation? What would in class flipping look like? 30 minutes of lecture to the middle area while outliers do independent video + reading, then 30 minutes of floating support while kids do problems and experiment or whatnot?