Here is the link: http://www.readworks.org/rw/about
The resources are FREE.
Here is the blurb:
The non-profit ReadWorks is committed to solving the nation’s reading comprehension crisis by giving teachers the research-proven tools and support they need to improve the academic achievement of their students.
ReadWorks provides research-based units, lessons, and authentic, leveled non-fiction and literary passages directly to educators online, for free, to be shared broadly.
The ReadWorks curriculum is aligned to the Common Core State Standards and the standards of all 50 states. Most importantly, ReadWorks is faithful to the most effective research-proven instructional practices in reading comprehension.
(PS: Thanks to Prudence Minton at Great Oaks Charter School for this lead!)