Using the Next Generation Science Standards Site, I have compiled the Disciplinary Core Ideas as well as the performance expectations for course 1, 2, 3 middle school (6th, 7th, 8th grade).
The document also gives the Practices and Core Ideas / Practices and Crosscutting Concepts next to the performance expectations.
I used the suggested model course mapping from the NGSS website. See page 11 of the following link to see the NGSS suggested model course mapping.
http://www.nextgenscience.org/si