Diagnosis of learning difficulties of plate tectonics concepts among secondary school students using: Focus group, nominal group, and questionnaireLarbi En-Nhili, Saïd Boubih, Mostafa Amiri and Mustafa El AlaouiE3S Web Conf., 412 (2023) 01061DOI: https://doi.org/10.1051/e3sconf/202341201061