Ask local elementary teachers which children in their classrooms are their best writers, and, usually, they will spontaneously name three or four students. Teachers know their best writers. They also know some of the contributing factors. These children are often good readers, who love a good story and seem to have a natural talent for telling one themselves. Where writing is concerned, they are a teacher's joy.
Bayliss, V. A. (1994). Fluency in Children's Writing. Reading Horizons: A Journal of Literacy and Language Arts, 34 (3). Retrieved from https://scholarworks.wmich.edu/reading_horizons/vol34/iss3/5