For an approved PRC series, students can read any five titles which will count as official PRC books in their reading records. Other titles read from the same series will show as Personal choice books. As students can include up to ten Personal choice books in their Reading Records, they are able to read and include up to 15 titles from the same series. Please refer to the Rules page of the PRC website.
The limit on series books encourages students to read a variety of genres and authors, rather than reading books from a few series or by the same author. Of course, once students complete the Challenge, they are encouraged to continue reading for enjoyment, either stand alone or series books.