In a flipped classroom, the students do their learning at home, and their work in class. Instead of the traditional model of the teacher lecturing during class time, the lecture is recorded in short videos (5-8 minutes each) that students watch at home as homework. Pre-recorded videos from YouTube or educational websites may be used as well. When the students come to class, they are ready to work. Instead of struggling with homework alone, the students are able to ask questions and correct mistakes as they work. The teacher is free to work with students individually or in groups to ensure that everyone understands the material.