We never paid any attention to levels here - partly because they never seemed relevant, partly because they were not emphasized at our children's school.
I just had to jump in though and say… um…. Dune for 5th grade? Yikes!
I played around with Lexile levels several years ago. What I found was that sentence length is huge, and what is considered a sentence is what is surrounded by periods. So, for example, I typed up a chapter of a Magic Tree House book. MTH is notorious for having sentence fragments everywhere. I used the Lexile analyzer to find the Lexile level of the chapter as written and then I went through and normalized the text, so that the fragments were incorporated into complete sentences. The only words I added were things like "and." Anyway, the grade level of the original text with all the fragments was something like 2.0 and the grade level of the properly written text was something like 4.0--which was what I was expecting.
I wonder sometimes if there is a bit of a geographic/school-district dependence relation that impacts reading levels - Magic Tree House books are definitely 2nd grade level here and many kids are reading them by the end of first (not talking gifted classes either). By third grade very few students in the classes I've helped out in were interested in them anymore -
Best wishes,
polarbear