finger slipped and my reply disappeared, I think!
I am after the same info. on fingering ,as the Nurture Minds curriculum uses 3 fingers, and everywhere else I see, including videos on competitors in Japan, uses 2.
Also, is there any benefit in reversing the order in which Big and Little friends are either added or subtracted?
My daughter has an easier time when she can deal with all problems the same way: either use the inverse number first in all cases, or do the adding or subtracting of 5 or 10 first, in all cases. But her workbook makes it very clear that when adding using an inverse number, it’s one way (I forget which, but say for our purposes it’s adding the 10 bead first and then subtracting the inverse number), and when subtracting using inverse numbers, it’s the reverse order of operations (first deal with the adding of the inverse number, and then carry the 10 bead, in this case subtracting).
I don’t get why it’s so important to do the carrying first in one case, and last in the other, so long as the kid understands that for overall addition, you must add the 10 and subtract the inverse for a net gain, and for overall subtraction, you must subtract the 10 and add the inverse, for net loss. Why does it matter to deal with the 10 first in one case, and deal with it second, in the other case?
But I have to assume there is a reason, because they are so exacting on it, just as there must be a reason for their careful training to use 3 fingers. Yet I know some of the leading competitors in the world use 2 fingers…I just wish I could find out if leading competitors also do their operations in reverse order with respect to the carrying bead, between adding and subtracting. I just need to know before committing. It would be sad to have my kids learn a method that slows them down, for no other reason than it was the first one I encountered.