Flipped Classroom model before and during COVID-19: using technology to develop 21st century skills. - Cecilia Latorre-Cosculluela; Cristina Suárez; Sonia Quiroga; Natalia Sobradiel-Sierra; Raquel Lozano-Blasco; Ana Rodríguez-Martínez (Interact. Technol. Smart Educ., 2021)