I will say that I had to laugh a little when I read:
Some advantages of strands could be that
(1) changing topics after a few minutes maintains interest
(2) if a student is stuck on a topic, he can still move to other strands and feel successful
I laughed because the former is the precise thing that drives my own top-down, mastery learner to distraction about the way that math (or anything else) is commonly taught in schools. She calls this the "ADD model of education."
My term is
ADD Mathematics.
My middle child is stuck with this model right now. Math class goes like this: "Let's do some absolute values! Okay, we've done our five minutes of that. We're going to move on to solving inequalities. Don't get too comfortable, though --- it's almost time for practice at order of operations!"
It's painful.
As for the strands thing, my impression of the Common Core stuff (I now have a
textbook written by Wu) is that the whole point of the CC is to tie it all together.
