The score is telling us that a reader with a 1145L may be best matched to books with lexile levels from about 100 points below to about 50 points above 1145L: books from about 1050L to 1200L.
You may have already read these links:
http://www.lexile.com/findabook/,
http://www.lexile.com/about-lexile/grade-equivalent/,
http://www.lexile.com/about-lexile/grade-equivalent/grade-equivalent-chart/. Playing with the find-a-book link by entering various grade levels shows that a 6th grade student who finds school books easy may be reading at a lexile level from 1040L to 1270L.
Yes, she is reading at a high level for her age of 8 years old.
The beauty of lexile levels is that one does not need to compare by grade levels or age, in fact some may say that doing so may seem to indicate a sense of using others in a grade level or age as foils or being less-than in contrast to a strong reader.
What some may take away is the selection of titles and genres of books available at your daughter's lexile level... screening for interest and content... voila! a potential reading list which is highly individualized.
