When looking for math activities, information, or new ideas I have a few “core” people I follow.
Here is the short list:
Bill McCallum: http://commoncoretools.me/author/wgmccallum/
Donna Boucher: http://mathcoachscorner.blogspot.com/
Dan Meyer: http://blog.mrmeyer.com/
Marilyn Burns: Math Solutions
Jennifer Bay Williams: Pearson
The “core” publications I turn to are:
Carpenter’s Work: Children’s Mathematics: Cognitively Guided Instruction
Van de Walle Series: Elementary and Middle School Mathematics: Teaching Developmentally
NCTM’s Series: Developing Essential Understandings (all grades)
The “Core” Sites and Resources I commonly refer to are:
This list is by no means exhaustive but if you are looking for quality math materials aligned to the “Core”, it is a good place to start.