The paper collects the theoretical reflections and good practices of differentiation instruction as a cultural and systemic approach of a school that aims at the educational success of students: in differentiation the learning and teaching processes enhance the talents of each one and experience inclusion as a design for all for an educating community.

Differentiating learning processes involves moving away from one-size-fits-all learning methods (Gregory and Chapmant, 2006) to recognize and stimulate the diverse needs and motivations of students, thereby encouraging self-regulation and persistence in education.

Tomlinson (2014) emphasizes the importance of creating learning environments where students can engage with different content and processes simultaneously, accommodating varying levels of readiness, interests, and learning styles.

Differentiated Instruction is a cultural, pedagogical, and organizational approach that values classroom diversity and motivates students to exceed their proximal development zone through collaborative learning; as noted by authors such as Tomlinson and Cunningham (2003a; 2003b), effective differentiation requires careful consideration of students, teaching methods, and strategies.

Differentiated Instruction should not, however, be considered as a set of strategies, methods and techniques to be used in the classroom but rather a way of ‘thinking’ about teaching and the teacher's work. A methodological perspective capable of promoting meaningful learning processes for all pupils in the classroom through a didactic design outlined on differences and aimed at proposing teaching activities targeted on the needs of individuals. Students have the opportunity to carry out the activities at their own pace, time, and learning style.

The "differentiated learning" methodology fosters a dynamic training environment designed for simultaneous, varied activities, promoting experiential, interdisciplinary, and research-based learning.

The need to develop didactic differentiation practices has strongly emerged in the pandemic, especially in Secondary school contexts, as a learning design to support the well-being of students and counteract school burnout of students and teachers. Formative assessment (assessment for learning, AFL) is the cornerstone of the educational culture of didactic differentiation, which accompanies the unfolding of learning processes, fueling self-regulation, self-efficacy, persistence and students' motivation.

The study investigates Italian school teachers' experiences with differentiated instruction before and during the pandemic (representative sample of more than 2500 teachers) through a national survey, focusing on the challenges of implementing differentiation, particularly in formative assessment and peer learning activities.

The research also explores key concepts such as cognitive processes, emotional learning, assessment for learning, and the role of educational technology, all underpinned by the principles of design for all and inclusion. Formative assessment, central to the educational culture of differentiation, supports learning by enhancing self-regulation, self-efficacy, and motivation.

Keywords: Differentiated instruction, self-efficacy, assessment for learning, inclusion, design for all.