This is the link to the 3rd grade site, but all levels can be accessed from this link. Note that it will be moving to another link at the end of the year.
Units for Common core
Instructional Technology Resources
This free site has reading and math common core activities
This site has nonfiction and fiction reading passages linked to common core Free
Leveled non fiction articles built around current events. Free
Leveled reading and comprehension questions variety of genres. Free
Activities for all content areas. Free version