 Education in the 21st century has changed in many ways. And by and large these changes are due to the availability of a gigantic pool of educational resources on the web. As one of my colleagues put it, the knowledge is now on the web and no longer just in the teacher's mind. In the following I will outline our reaction towards this new challenge and I will introduce the educational philosophy that we use on the virtual linguistics campus. The label we have created for our scenario is the inverted classroom mastery model. The foundations of this educational model go back to Maureen Leigh, Glenn Platt and Michael Treglia who introduced the concept of the inverted classroom in a paper presented to the Journal of Economic Education in 2000. In this paper they described the need to serve a wider variety of learning styles in class. We picked up their ideas in 2002, applied this model to our linguistics classes and introduced it in print first in 2006. Realizing that a simple version of the inverted classroom model is not sufficient for our needs, we expanded it to the inverted classroom mastery model in 2009 and described this new scenario in our main publications in 2012. In order to understand the central implications of the inverted classroom and its expansion, let us look at traditional education first. In traditional teaching and learning scenarios, content delivery and content acquisition are realized in class. In a second phase, students practice on their own, on the basis of additional exercise material, homework tasks, etc. In this traditional model seen from a student's perspective, phase one is the least interactive part of learning and phase two is most interactive. So why not flip or invert these two activities? Well, this is exactly what the inverted classroom does. Content acquisition is now self-guided. It takes place first, it is based on digital media and it is done online. The additional in class phase is dedicated to practicing, to rehearsing, to discussions, to the analysis of data and so on and so forth. This means prior to each in class meeting, students must have worked through the online content of the respective unit. How does this work on the virtual linguistics campus? Well, in phase one, students are now autonomous learners. They are given the content by means of a multi-modal e-learning unit. In all our classes, we supply our students with highly interactive multimedia content, the so-called virtual sessions. Furthermore, they can watch our e-lectures and use the active board content on which these videos were produced. And last but not least, they can use the optional workbooks which supply them with the text material of each unit and give them the opportunity to supplement the text with the online content. Students now have access to the content as often as they like and from wherever they like. They can examine the virtual sessions with almost no limit. They can watch the e-lectures on their mobile devices. They use the e-lecture board content and they supplement their workbook with the missing information. And once they're ready and have mastered it all, they attend the subsequent in-class meeting. Now, the in-class phase is now no longer any sort of frontal teaching. So this sort of scenario is no longer a suitable teaching and learning scenario. Instead, the central teaching method is that of a cooperative interaction between instructor and students. Honestly, for us it doesn't make sense to teach in the traditional format anymore. Why should we repeat what's in an e-learning unit? So what we do in class instead is practicing, discussing problems, analyzing data, all those things that our students would have done on their own at home without any assistance. Now we do the homework, if you wish, in class. We discuss problems with our students and collaborate. Thus, typical in-class scenarios look like these. And here you can see the instructor right in the middle of his students' activities. He provides help. He gives advice and is available for questions. And the students all work on specific tasks. Non-interactive frontal teaching, well, that's no longer a desirable option. Now, the inverted classroom model presupposes that students must have understood the content in Phase 1 before they join the subsequent in-class phase. But how can we ensure this? The solution to this question is quite simple. We have to expand the model by a new phase which gives our students a chance to demonstrate mastery of content and skills before the in-class phase. So the gap between Phase 1 and Phase 2 must be bridged by an additional phase that we refer to as formative assessment. In the case of the educational model used on the virtual linguistics campus, these are of course electronic tests. Students who pass such an electronic test have demonstrated mastery and can believe to be well prepared for the subsequent in-class phase. And students who do not demonstrate mastery by either not passing or simply not doing the electronic test have additional options. They can repeat the test until they pass it. They can go back to the phase of content delivery as often as they like and then tackle the test again. Or they simply attend the in-class meeting without having demonstrated mastery. For some students, this may even be a standard option. They feel that they have mastered the content without showing mastery via an additional test. And in a worst case, they attend the in-class meeting totally unprepared. However, according to our experience, this last option is the least desirable one. Relatively quickly, they realize that without preparation, it doesn't make sense to join their fellow students in class. Well, and how does the e-assessment work? Well, the backbone of the virtual linguistics campus formative assessments is a variety of electronic tests presented using the interactive tutor. Tests with sound support using virtual keyboards, listening tasks, selection tasks, input tasks as well as multiple choice. These electronic tests in the virtual linguistics campus terminology they are referred to as worksheets are important tools for us instructors to find out whether our students have mastered the online content or not. And for the students, well, the worksheets are not graded but only have to be passed. And if students don't pass them in a first attempt, no need to worry. They can try as often as they like and no one will notice. Only in the case of success, the successful attempt will be stored in the VLC database. And as an instructor, a quick look into the class-related database determines the organization of the in-class phase. If the majority of students had trouble with the worksheet, we can assume that they have not mastered the content, thus we will have to reteach. If all students or the majority pass the worksheet, we can assume a high degree of mastery and the focus will be on practicing. Well, and if it's somewhere in the middle, we will do both. So the worksheets are formative assessments in the true sense. Their results shape the organization of the in-class phase. Here is a fragment of a class-related spreadsheet to which the VLC class instructor has access via mouse click. It exhibits the situation after two worksheets and shows that almost all students have mastered the E-test. Only student number 58 either had trouble or didn't care. But we can sort this out in class because our role as class instructor is now completely different. As Allison King, a former educational psychologist from California State University predicted in 1993, we have completely changed our role. We no longer sage on stage but guide on the side. We do not deliver content in the traditional way anymore. We do not bore our students with lengthy presentations about topics such as the phoneme, speech act theory, or how the subject of a sentence can be identified, to name a few linguistic topics. Rather, we supervise our students' activities. We try to motivate them to do their tasks in time. We make sure that everyone is served as well as possible and we now have the time to do more efficient things with our students beyond mere content delivery. For example, we can help those students that have mastery problems such as our student number 58. Or we can provide additional tasks to our most advanced in-class participants. So let's summarize. With the availability of web-based learning materials such as multimedia, video and print, the majority of our linguistic classes have been reorganized according to the inverted classroom mastery model since 2004. Now content delivery takes place online and serves as a prerequisite for subsequent in-class meetings. The in-class meetings are now predominantly used for practicing and analysis. And formative assessments serve as a bridge between the online and the in-class phase and are used to examine content mastery. Our roles as teachers have changed dramatically. We are now guides and partners of our students rather than masters of content delivery. For our students who have been brought up as digital natives by contrast, this scenario has become increasingly normal. Well, and as our permanent class evaluations and the comments by the VLC community have shown, our students are not only used to their new role, but they also seem to like this educational scenario. And most importantly, as first knowledge-based evaluations have shown, long-term memory effects are now more significant than in traditional teaching and learning scenarios. So we will continue using the inverted classroom mastery model and we will not only improve our web-based learning materials, but we will also work on new concepts for in-class activities. If you want to join us or have any ideas in this respect, you're welcome.