I have been interviewing a lot of developers recently, and one of the best questions I've found is to ask them _why_ they have used MVC pattern in the test assignment (most do). Most of developers misunderstand the question at first and either start to explain how MVC works or explain how they would've implemented it without MVC (when you ask people why they did something, they often take it as "you shouldn't have done it"). But even when I clarify the question, a surprising number just can't even begin to answer it — instead they stumble and at best just tell that that's how they have always been taught to do it.