"Understanding Screenwriting" dissects 21 successful and unsuccessful screenplays. It analyzes why certain aspects of a screenplay work and others do not.This is an opinionated book, not in any way meant to be a comprehensive survey. Like any opinionated book, especially one aimed at students, this one rises or falls on the sure-handedness of the author. Stempel is engaging, responsible and level-headed. "This book isn't about me, it's about you" is the way it begins. "I am a teacher, not a guru. As a wise teacher once said, with a guru it is all about the guru - his vision and the students' loyalty to him. Whereas with a teacher, it is all about the students learning...You should be reading this book because you, as screenwriters, directors, producers, development executives, critics, historians, students in those disciplines, and just plain movie fans want to learn about screenplays." Above all, Stempel gets the reader to see as well as to think as budding screenwriters.There are 21 films discussed at length along with 52 short bits. What Stempel has attempted is a cross-section: adventure, sci fi, horny-teenage, romantic comedy, history - films mostly of large budgets that many people would have seen. To give a few examples, Stempel looks at how the script of "Lawrence of Arabia" varies from the source; "Rear Window", further discusses screenplay adaptations; in "Fargo": he asks why a screenwriter would introduce a hero so far into a script; "Bull Durham" begins with a monologue. Stempel aims for an 'interactive approach' and is successful in drawing in the reader.