Common core is a specification that is implemented many, many times. It's not just each textbook or school system - each teacher will implement the spec in a un

Common core is a specification that is implemented many, many times. It's not just each textbook or school system - each teacher will implement the spec in a unique way. With so many implementations, some of them are going to be terrible. But the common perception isn't built off an average or large-scale aggregate, it's built on what people see and hear. A single comically bad implementation can be seen by millions of people thanks to Reddit, Facebook, and the like. A single good implementation will be seen by the students, maybe their parents, and maybe a few more teachers. Most examples people see are comically bad, so the common perception is that common core is comically bad.