What is the author's style in The View from Saturday by E. L. Konigsburg?

The novel is simply written and should be easy for the average middle school student (or older) to read. The "voice" changes in the chapters where one of the four students, Noah, Nadia, Ethan, or Julian, is narrating in the first person. Noah's voice is marked with his use of the word "fact." Nadia has a precise and careful voice, eschewing contractions and slang. Ethan's voice is full of descriptions of what he sees; of the four students, he is most attuned to appearances. Julian's voice is precise, like Nadia's, but uses some British idioms and words in keeping with his upbringing and education.