Teacher training and innovation in the academic field are basic processes for improving the quality of education. This paper presents an innovative didactic experience for students of the Master’s Degree in Teacher Training in Secondary Education and bachelor’s degree, of an online university, in the specialty of mathematics. The educational innovation arises after the detection of difficulties in the assimilation of the contents taught in the subject of Teaching Innovation and Initiation to Educational Research by the participating students. The experience consists of a real simultaneous interaction (online) between the students of the Master’s Degree in Mathematics and the students of bachelor’s degree of a public center of Secondary Education, in Spain, while they receive classes in their center in a face-to-face way. The didactic methodology used in this experience is based on the principles of the Flipped Classroom and, at all times, the material necessary for its understanding and assimilation has been shared with the Master’s students. To analyze this experience, a questionnaire was used to collect information before and after the experience, a satisfaction survey and a focus group. The results indicate that the students of the online Master’s program consider this experience very necessary, since it favors the perception of the environment to which they must adapt and, in addition, the visualization of real cases provides a significant vision that completes and complements the theoretical training received. [ABSTRACT FROM AUTHOR]