How Johnny Adds 2+2

According to Carol Peterson, "I think the children
truly understand math instead of just memorizing it."

According to Rob Canada, "the traditional way worked
only for people who could jump through the hoops."

Are these two on top of their game, or what?

Dom Rosa

fishfry...

As many bad things as I've heard about the "new new" math, I have to say
I agree with this example. This is exactly how I do the problem too ...
start with 78 and add 10's till you get to 98, then add 1's.

Dom...

My problem is not with doing mental calculations like the above or like
those
posted in other replies. I question the overreliance on "number
charts," "algebra
tiles," and other "manipulatives" to do the simplest of calculations.
It is truly
amazing to see how stunted the minds of so many students are, and the
difficulties that they have, even though they are armed with graphing
calculators.

If there is a problem with this approach, it would be that not everyone
"gets it." Not everyone is destined to be a math/computer type. In order
to use this approach, you have to instinctively perceive 78 in relation
to 100. That's the math gene, which is abundant on this board, but not
in the general population.

A course like this must be very difficult for the future liberal arts
types.

Jim Langston...

I'd do it the same way but a little different. I'd jump to 80, then by 10
to 100, then add the 2 back in. The reason I think I do this is to find the
quickest approach. If it was 48 cents, I'd jump to 50, add 50 then add two,
rather than 48 by 10's to 98.