The main objective of this work is to analyze the students’ opinion and the use they make of a series of videos performed to prepare the laboratory sessions given using flip teaching methodology, in courses of physics and electricity of the first year of the Degrees on Electronic Engineering and Industrial Design Engineering of the Universitat Politècnica de València (UPV, 170 and 140 students are following each Degree, who are divided in 8 and 7 groups for the practical sessions at the laboratory. A traditional oral explanation for students which such a big number of groups is a problem from the point of view of giving all of them a uniform information to perform the laboratory experience. Flip teaching solves this problem: all the students have the same information at the same time and it has to be consulted before each session at the laboratory to be able to perform the experience properly. Moreover, flip teaching, when used this way, reduces the time dedicated to explanations, which allows the teacher to spend more time supervising the work made by the students.

The videos have been made in screencast format (with and without the image of the teacher) and in Polimedia format (a system designed by the UPV to create multimedia contents in a studio). The length of the videos is common to all of them being between 10 and 15 minutes, they have been recorded in Valencian, Spanish and English, and their contents are related to the measurement theory, utilization of electrical equipment of the laboratory, mechanics, elasticity, electrical circuits, ... which are used in 14 experience of similar difficulty. After the laboratory session, the students must prepare a report, that has to be sent to the teacher within 10 days.

The objective if this communication is to check if the following hypothesis are right:
H1. The students see the videos before the laboratory session, following the way in which they were designed.
H2. The students prepare audiovisual material that the written one.
H3. The students consider than the quality, length and contents of the videos are enough to prepare properly the work they have to do during the laboratory sessions.

To do that, statistic data about the consultation of the videos available via web have been analyzed, the students’ opinion has been obtained by using surveys with open and closed questions and interviews.