Barry Garelick's recent piece Education News, Undoing the ‘Rote Understanding’ Approach to Common Core Math Standards, got me thinking about one of the things that Reform Math has backwards.
Barry talks about the emphasis by today's math educators on ad hoc methods like "making tens" at the expense of traditional algorithms like borrowing and carrying. And so we see more and more worksheets like this one:
And fewer and fewer like this one:
And, in promotional, Common Core-inspired videos like this one, we see just how painfully slow the "making tens" method can be--as well as how it, by itself, does not give students a general method for solving more complex addition problems.
As I wrote in a comment on Barry's piece, I don't remember ever learning officially how to make tens. I remember it instead as something I discovered on my own--in the course of computing all those long columns of sums that students used to be assigned (sometimes upwards of six addends!) and eagerly looking for shortcuts.
The standard algorithms, on the other hand, I most certainly did *not* discover on my own, and am quite glad to have had teachers that were willing and able to teach it to me.
It's ironic how "discovery-based" Reform Math spends more time showing students how to do stuff they might discover on their own than it spends showing them how to do stuff they almost certainly won't learn on their learn own.