# YouTube Videos in the Virtual Flipped Classroom Model Using Brain Signals and Facial Expressions
## 2 Methodology
### The Participating Population and the Procedure
These waves are slower and of greater amplitude than the beta waves. Their frequency ranges from 8 to 14 cps. A person who has finished a task and sits down to rest, or is taking a walk or enjoying the landscape, is often in an alpha state. **Theta Waves**  
These waves have greater amplitude and lower frequency (between 4 and 8 cps). They are reached under a state of deep calm. Individuals in this state include those fantasizing (or daydreaming), or someone who, after driving for some time, suddenly realizes that they do not remember how they have driven the last mile. This state is said to be a state of inspiration for creative ideas and solutions, and is a state in which the tasks carried out have been automated; it is no longer necessary to have an attentional and conscious control of their execution. **Delta Waves**  
These are the waves with the highest amplitude and lowest frequency (between 1.5 and 4 cps). They are generated in a state of \"deep sleep\". During sleep, the brain waves change successively from beta to alpha, theta, and finally, delta; these cycles last about 90 min. Figure 4 shows an experiment on brain activity when a video is played in different video segments. Thus, each signal can be studied to determine the concentration level. Figure 3: General description of the EEG using a computer. In addition to this record, the student's reaction to the videos was also qualitatively evaluated using _Emocards_[28]. The students' emotions were recorded using a camera when they were stimulated by the video (see Figure 5). This system made it possible to assess the students' perception of the video in terms of attention and emotion. This procedure was an essential contribution because the detection of the student's responses offered information about how they were being stimulated audiovisually, and how they were feeling as a result of the presentation of the academic content of the video. Using the student's response, it was possible to design and evaluate the videos. In addition, the videos were able to be made more attractive, thus increasing their adoption. Hence, both processes were used to validate the existing materials and to design more attractive new materials. Various department professors designed the videos. As a result, the participating professors were required to become familiar with the videos they did not design. In the Results section, the teachers' opinions on this and other items related to implementing the model are presented. This feedback was obtained through an applied survey. The subject of this study was a pilot course in which a new distance methodology was implemented to improve grammatical competency, and designed to work at three levels (basic, intermediate, and advanced) for a more personalized and differentiated instruction. As a result, only three teachers participated. Their ages ranged between 35 and 45. Their training was in the Spanish language, at the level of master's studies, and they had between 10 and 15 years of experience working in the educational institution at which the study was carried out. They were familiar with the use of digital resources in teaching and the Flipped Classroom model. Figure 4: Experimental results regarding the brain activity, recorded during different times of the video. The colored bar shows the power of the signal (frequency of 19.5 Hz)—darker high power, lighter low power. Figure 5: Emocard emotional distribution [28]. The design of the learning activities was the responsibility of each participating teacher. According to the learning styles of their students and their teaching style, the teachers designed a menu of specific activities that included these variables: reflective, active, sensitive, intuitive, visual, verbal, global, and sequential. In the final synchronous session, students took a final test to measure their grammatical proficiency, and the results were compared with those of the first test.