Bad. Trying to teach all children to learn the same way never works. Different people see things different ways, and teachers need to be able to have the freedom to teach in such a way that they can reach all the students.
Common Core. Good idea or Bad idea?
It would depend on how they push the "Common core" ethics. To try and assure (and I mean try) that all have the roots of modern education is the goal is good, the effort to teach all the same way is wrong. Not all learn on the same level or the same way.
A lot of people really have no idea what common core is. I've encountered plenty who consider it some kind of communism brainwashing mechanism created to change history and turn our young into Nazi sympathizers. Give me a break.
It's just a guideline for maths and English. All it is.
The math part, I really like. It basically teaches maths on paper exactly like how we would normally solve it in our head. This builds a more solid foundation for when they get to more difficult mathematics in college. I notice a lot of kids struggle with upper level math because all they've been taught since little is to memorize formulas, plug in the numbers, and get the results. Sadly, that doesn't work when you get to a certain level. You have to actually understand the maths and why it happens in order to solve anything.
Here's a few examples. It's meant to be satire, so it's actually the reverse. imgur.com/a/kE6Ws