Resources to Guide Common Core Implementation
A site for anyone in the building, district, or private sector that is involved in math education. This particular page from the site is a link to their ever-growing set of resources directly related to the common core; however, the large site will reward anyone who spends time reading and opening its many links. It is particularly well-suited as source for professional development in mathematics both as it relates to the common core specifically, but also math education in general.
I can’t help but direct you to their amazing set of resources on fractions–a must see.