Middle School materials:
All states will have to have separate discussions about middle school. The grade breakdown of middle school varies state to state and the subject taught in each grade level varies. In California, typically, 6th grade is Earth Science, 7th grade is Life Science and 8th grade is Physical Science. California has already put out their proposed arrangement of the Middle School NGSS by grade level here. Each grade level had a chart of the topics, I combined them below.
Crosscutting Concepts are concepts that should appear in multiple
disciplines and help students see the overall interdisciplinary
connections between their classes. Often, teachers discuss applications
of a particular concept in multiple classes. For example, the lens of
the eye shares properties with over convex lenses so it may be discussed
in both a biology (or anatomy) class as well as a Physics class. In my
class I discuss near-sightedness and far-sightedness and how their focal
lengths differ; students who are in anatomy and have dissected a cow's
eye have a much better understanding of that concept.