Free App for Common Core - Common Core Standards, by MasteryConnect, is a pretty solid "free" CCSS app if you want to pull up the standards any time, anywhere. Recent updates now include all subjects, including language arts, traditional and integrated mathematics, history, social science, and science and technical subjects. Click on a subject then a grade level, and then select a standard to drill into the actual standard language. In the history and science areas, select a grade level and you can drill down into the reading connections with corresponding college- and career-ready anchor standards.
White paper by McTighe and Wiggins