Middle Grade books, for readers ages eight to twelve, can cover multiple topics (mysteries, family issues, sports, adventure, etc.) and time periods (past, present or future.) Stories can be humorous, exciting, grim, imaginative (science fiction or fantasy), or a combination. A primary requirement is that the protagonist is well developed with multiple traits to the extent that the reader should feel like he/she know this child and would recognize them on the street. There can be multiple characters, but all of them must be distinguishable to the reader. Traditional lengths for Middle Grade books are 20,000 to 40,000 words, though the Harry Potter books clearly challenged traditional guidelines.