Utah Core Standards for Elementary Mathematics Resources

The Common Core State Standards website
http://corestandards.org/the-standards/mathematics

NCTM's website Illuminations
http://illuminations.nctm.org/

Illustrative Mathematics
http://www.illustrativemathematics.org/standards/k8

Inside Mathematics
http://www.insidemathematics.org/index.php/common-core-standards