The Oracle Series is featured on Accelerated Reader by Renaissance and also has official Lexile scores. :)

Accelerated Reader

(click this link, then search “Trisef”) — first editions of books 1-5 were rated at 6th and 7th grade book levels, with points ranging from 12 to 17. Second editions of books 1-5 and first editions of books 6-7 are currently under revaluation.

Accelerated Reader engages students in reading practice with authentic books by strengthening reading skills essential for learning in any subject and by practicing with comprehension quizzes and close-reading activities.

Lexile

(click this link, then search “Trisef”) — all 7 books measured between 880L and 1010L (5th grade).

Lexile measures provide a scientific approach for matching students with ability-appropriate text and audio resources. Lexile measures help differentiate instruction and monitor growth in reading and listening, putting students on the path to success in school, college, and careers.