The flourishing of multicultural societies worldwide during the last few decades has lead inevitably to multicultural, heterogeneous and mixed ability classrooms. Schools face many issues that come from the increasing diversity of student population. Teachers teach students characterized by cultural, ethnic, racial and linguistic diversity. Educational manifestos such as the ‘No Child Left Behind’ (Guilfoyle, 2006) claim that teachers should engage all students in learning, responding to their individual needs.

Teachers nowadays fail to meet the diverse academic needs of their students.  “Research reveals that educational systems fail to meet the challenge of providing quality and equity, leading to an achievement gap between different groups of students.”  (Valiande et al, 2011, p. 2). Teachers should give students the opportunity to develop and demonstrate their skills as well as their knowledge through a variety of teaching methods (Erwin, 2004) so as to promote democratic and equal paths of high quality learning.

According to Valiande et al. (2011) educational systems have failed to fulfill their mediating role and have not found the way to be effective for all. Therefore,Tomlinson (2004) mentions that differentiated instruction is the answer to low academic scores. Students’ academic needs are met at an optimum level, in classrooms where teachers utilize the approach of differentiated instruction.  Differentiated instruction is defined as teachers’ responsible reaction to learners’ individual needs. Teachers should differentiate curriculum in content, process and product according to student readiness, interests and learning profile, followed by ongoing assessment and flexible grouping. Unfortunately, teachers tend to categorize students with special needs based on their low academic scores and continue to teach so as to satisfy the average student. According to Christenson & Wager (2012 ),   O’   Roark (2013) and  Tomlison (1999) when teaching is characterized by differentiation, students have the opportunity to obtain higher academic scores and achieve better outcomes. Kobelin (2009) and Phelps (2012) have also shown that the implementation of differentiated instruction has a positive influence on student achievement.

Even though researchers recognize the existence of multiple differences of students in mixed ability classrooms, teachers do not appear to differentiate their instruction. Florian (2008) mentions that the mainstream teacher is an important factor for the success of inclusive education where teachers are called to respond to their students’ diverse academic needs. Teachers nowadays should compose an extremely demanding and differentiated academic environment, which includes all students, so as to ensure the basic human right of effective and  quality education. This is possible through the use of differentiation. According to Tomlinson and Allan (2000) “differentiated instruction can help address the needs of academically diverse learners in our increasingly diverse classrooms” (p. 1).

The theoretical framework of differentiated instruction is grounded on Vygotsky’s learning theory of cognitive development which implies that a major factor for the development of a student is a shared endeavour between student and teacher (Tomlinson, 2004). Moreover, differentiated instruction is linked to Vygotsky’s Zone of Proximal Development (ZPD). Vygotsky (1978) defines ZPD as the distance between the actual development level and the potential development. Teachers should take the role of mediator and allow learners to attain their ZPD.

The purpose of this piece of research is to investigate the effectiveness of differentiated instruction in Greek language in the third grade of a State primary school.

This will be followed by an intervention research guided by the following research questions:

1. Does flexible grouping of students according to their interests, readiness and learning profile help all students obtain the maximum of their academic achievement?

 2. In what degree does class size affect the success of differentiated instruction?

3. Which are the techniques that help students raise their academic achievement in the Greek language lesson?

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