MUSTAPHA AL- HARBAWI, K. Level of Difficulty in Teaching Mathematics at the secondary Stage in the Light Reforming the Curriculum and its teachers’ Point of view. College of Basic Education Research Journal, [S. l.], v. 13, n. 2, p. 1–40, 2014. DOI: 10.33899/berj.2014.Vol13.Iss2.39291. Disponível em: https://berj.uomosul.edu.iq/index.php/berj/article/view/39291. Acesso em: 2 nov. 2025.