Classroom Resources and Sample Assessment Items
http://www.parcconline.org/classroom
Sample Mathematics Tasks
http://illustrativemathematics.org
Resources and PD Modules
http://www.achievethecore.org
Dr. Bill McCallum's Blog (one of the writers of the Math CCSS)
http://commoncoretools.me
A series of video vignettes that explain the Standards in far greater depth.
http://www.ccsso.org/Resources/digital_resources/common_core_Implementation_video_series.html
Learning Progressions from National Center for the Improvement of Educational Assessment
http://www.nciea.org/publications/Math_LPF_KH11.pdf
Learning Progressions from University of Arizona
http://ime.math.arizona.edu/progressions/
New York Common Core Resources and Assessment Resources
http://engageny.org