Ian Bogost exams the flipped classroom in The Atlantic.
A traditional classroom has readings before class, lectures during class, and assignments after class. A flipped classroom has lectures before class, assignments during class, and assessments after class. Flipped classroom supporters like to argue that traditional classrooms only provide first exposure to materials via lecture, but that claim assumes that nothing whatsoever happens before such classes, that students enter class blind. In reality, digging deeper than hearsay is a hallmark of university education. Classes in all disciplines ask students to engage with primary and secondary materials beforehand.
The flipped classroom abstracts these materials, overloading them into the lecture, which itself is usually shortened and condensed into modules less than 20 minutes in length. This condensed primary material then becomes fodder not for discourse or practice, but for evaluation.