The acquisition or improvement of teacher competences requires training, through which it will be improved educational planning and assessment. This results in a better learning of students, as evidences show. It is the objective of FAMT & L Comenius project, conducted at the University of Bologna, designed with the aim of promoting the correct use of formative assessment in mathematics education for students aged from 11 to 16. Reaching this goal supposes to design training programs for teachers of mathematics, starting from identificating their needs, believes, expectations and the use of formative assessment.