Middle grade
This is the golden age of reading for many children, ages 8-12.
Manuscripts suddenly get longer (100- 150 pages), stories more complex (sub-plots involving secondary characters are woven through the story) and themes more sophisticated.
Kids get hooked on characters at this age, which explains the popularity of series with 20 or more books involving the same cast.
Fiction genres range from contemporary to historical to science fiction/fantasy; nonfiction includes biographies, science, history and multicultural topics.