Is forming ability-based classes the solution, then? In October 2023, when Education Minister Gabriel Attal raised the possibilityof organizing ability-based groups in math and French for middle school instruction, he reignited a debate about class composition that has been recurring for over a century.
Proponents of ability-grouped classes focus their arguments on the better tailoring of teaching practices and the resulting effectiveness. For others, mixed-ability classes are a factor in social cohesion and the reduction of inequalities. What is the reality? What impact does the grouping of students have on teaching, the school climate, and student learning?
Numerous international studies in the field of the economics of education have focused on the peer effect. This research examines the influence of the characteristics of other students in the class—particularly academic achievement and socioeconomic status, which appear to be strongly correlated—on the performance or well-being of a given student. Overall, these studies show that class composition (heterogeneous vs. homogeneous) has no effect (or only a very small effect) on students’ academic performance.
Furthermore, although there is no clear consensus, these studies suggest that high-achieving students would benefit more from homogeneous classes in terms of their academic performance, while low-achieving students would benefit more from heterogeneous classes.
With regard to well-being and social attitudes, the literature tends to show that heterogeneous classes are more conducive to their development. In France, a recent study by the CSEN (Scientific Committee on National Education) reveals that, while greater social diversity in middle schools has no impact on academic performance, it does have positive effects on personal and social well-being for students from both affluent and disadvantaged backgrounds.
These studies provide valuable insights into the effects of class composition. However, they overlook a key element of learning and classroom dynamics: teachers’ instructional practices.
It is generally accepted that ability-grouped classes, through teachers’ instructional practices, can widen the gaps between students in lower-level classes and those in higher-level classes. Indeed, teachers tend to lower their expectations and engage students in less reflective thinking in classes perceived as weaker.
Furthermore, research has shown that the higher teachers’ expectations are regarding their students’ engagement and academic performance, the more their teaching practices support their students’ motivation and learning.
Other, less common studies have examined the effects of class composition on academic performance, taking into account the quality of instruction as measured by three categories of teaching practices:
teaching strategies (adapting learning situations, encouraging students to use problem-solving strategies, etc.);
emotional and social support (encouraging students, being available to them when they face difficulties, etc.);
classroom management (engaging students, preventing disruptive behavior, etc.).
While the results from elementary school do not show that class composition affects the quality of instruction, they do reveal that the more heterogeneous the class, the more significant a role the quality of instruction plays. In other words, teachers’ instructional practices appear to have a greater impact on students’ learning and progress when the class is heterogeneous.
Furthermore, preliminary results from an ongoing study of 145 secondary-level classes suggest that teachers’ perceptions of classroom heterogeneity lead to instructional practices that have conflicting effects on student engagement. In particular, the more teachers perceive their classes as heterogeneous, the more they support students’ sense of competence (notably by clarifying expectations and adapting learning situations), but the less they encourage the use of higher-order cognitive strategies and student autonomy.
Ultimately, even if heterogeneous classes do not affect academic performance, they do have positive effects on students’ well-being and social attitudes. Furthermore, it is in these types of classes that teachers’ instructional practices seem to play a key role in student success.
However, the realities of the classroom also reveal the challenges teachers face in managing this type of class, which requires them to differentiate and personalize their instruction even as class sizes remain large. Consequently, several questions warrant consideration.
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First, beyond comparing ability-grouped classes with heterogeneous classes, future research would benefit from refining the measurement of the degree of heterogeneity within classrooms (e.g., the proportion of students at each ability level and the gap between ability levels). Indeed, it is worth asking whether there might be an optimal level of heterogeneity that is conducive to student progress and teachers’ instructional practices.
It also appears that a flexible classroom structure that combines heterogeneous classes and ability groups can facilitate differentiated instruction and benefit students. With this in mind, students in a heterogeneous class may occasionally join ability groups for specific learning activities.
This organizational approach is sometimes used with middle school students for certain fundamental learning areas so that students can temporarily benefit from instruction tailored to their needs while continuing to work toward common goals. This is also the case in elementary school, in multi-level classes where ability groups are formed on an ad hoc basis. With this in mind, attention must be paid to the integration of teaching practices and subject-specific content in both initial and continuing teacher education programs to help teachers develop the professional skills needed to better manage student heterogeneity.
Finally, we need to consider the strategies that enable teachers to better manage heterogeneous classes and that are effective in helping students make progress. In this context, co-teaching (two teachers per class), even with larger class sizes, appears to be a promising approach. Indeed, it offers greater flexibility through the sharing of tasks—such as classroom management, academic support, and emotional support—which facilitates differentiated instruction and the management of heterogeneity.
However, co-teaching is not a magic solution; it requires a specific organizational structure within the school, appropriate oversight, and high-quality teacher training.
