If you haven't seen this or a similar article lately, I envy you. If you aren't aware of the issue, let me briefly explain.
As part of the new Common Core curriculum changes, the way we teach math in the US is going to change dramatically. The article I linked is one example, but there are others if you google around. At a high level, what they are trying to do is switch from the broad but shallow way we used to teach math (many topics covered only for a day or two each, teaching students just enough to be able to solve the problems in the textbook) to a more focused, but deeper curriculum that gives students time to fully understand the important foundational concepts.
Specifically, they are moving away from teaching formulas, tricks and shortcuts for solving problems, and toward teaching underlying mathematical concepts and creative problem solving. This is where people are flipping their shit.
I'm going to briefly be sympathetic toward these people and say that I can understand it might be difficult when your child comes home from school with homework that you can't help them with. Your immediate reaction might be to get angry and defensive because there must be something wrong with the school if you can't understand elementary level math. I implore you, however, not to do this. Just because it isn't the way you learned it, doesn't mean that it is wrong. In this case, I argue, it is actually much, much better. You were done a disservice when you were taught math, please don't let your insecurity prevent your children from learning and loving it.
As an example, the new method of subtraction is much easier and more intuitive than the "grade school" way of doing it. Instead of starting with the higher number and removing from it another number, the new way starts with the lower number and counts up to the higher number. If this sounds familiar, tellers have been doing it forever when they give you your change. For instance, if you give them $20 for a $3 drink, they count back "four, five, ten and twenty." You can teach a student to do subtraction using the old "borrowing" method, and they will be able to do it, but they won't understand why, which sets a bad precedent. The counting up method is easier for large or irregular numbers, and it even introduces you to some concepts of algebra. I also guarantee you that anyone who works with math regularly already does it this way in their head.
There are going to be some growing pains, particularly for students that are caught in the middle, having learned the old ways for several years and now being abruptly switched to new techniques. In the end though, I predict that it is going to get a lot more students learning and loving math, especially those that were turned off by the old paint-by-numbers way of doing it. I could write a whole other post about the sad reality that some students are met with in college when they realize that they aren't really good at math like they have been told their whole lives, they are really just good at following directions. It is damaging to teach math that way and I, for one, am glad that we are finally taking steps away from it.