The use of video screencast is a useful tool to support teaching. In this work we have evaluated the influence of this videos used in three different ways. In a first method, we recorded some instrumental videos explaining to students general procedures to solve physics problems. The purpose was to introduce students in general methodology. In a second method, we used this videos to reinforce some explanations and theoretical concepts previously explained in class. The main purpose of this second method was to help students to understand the most complex concepts of courses in order to avoid the main difficulties. The third method consisted or recording some videos in order to explain students the main procedures to be followed in the laboratory. In this methodology, students had to visualize videos before coming to the laboratory and they should be able to work with no additional explanation from the instructors.

In order to evaluate the effect of these three different methods to use screencasts, our students answered a survey expressing their opinion. In general they have a positive opinion on this videos. Students consider that this material can complement their traditional way of learning and this can improve their knowledge on the subject.

We can conclude that all three methodologies can be helpful for students to learn physical concepts and more work is needed in order to explore if a more intensive use of videos can be more productive in this sense.
keywords: screencast, videos.