As shown above, NGSS identifies four core domains of science; life science, physical science, earth & planetary science, and engineering and technology. In the past, these domains have been mostly taught at different grade levels (6th = earth, 7th = life, 8th = physical). However, as scientists know, rarely is one domain used at a time. Therefore, NGSS adopts an “integrated” model where the four domains are blended within each grade level. Below is a rough cheat sheet of the content taught at each grade level, though it may vary within classrooms and by teacher.