Your student is most likely ready to read books at Level P.
Books at this level have complex sentences and vocabulary. The themes are increasingly abstract and include issues that are less familiar and require thoughtful reflection. The nonfiction texts have a range of text features and vocabulary that may be unfamiliar. There will be new words that require solving by taking words apart by syllables or by using base words and affixes. There may be words they can easily read but are unsure of the meaning.