The size of the class is important

The academic organization of students within a school depends on the resources available at each school. This includes:

• Personal resources: the number of teachers, specialists, administrative staff, services, and parents.
• Material resources: teaching supplies, furniture, and materials for didactic use.
• Functional resources: time, money, and teacher training.

When deciding class size, other factors should be taken into account like institutional history and the social climate of a school. School faculty need to be aware of cultural conceptions and expressions manifested or present in student's grouping systems.

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The influence of the size of a class in terms of the number of students per classroom impacts learning. It is the job of educators to determine any issues that may arise with different class sizes and how to use class spaces for groups of students.

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In research by "P. M. Hollingsworth in Class Size: An Educational Issue, Education" (1990), he compiled studies on this topic since the beginning of the century and pointed out the antiquity of interest in this subject. He reminded us of those first investigations related to the number of students per classroom and effects on performance and grade promotion.

Later research on class size emphasized the influence of the number of students on academic achievements only. These days studies on class size are more methodological to determine the best size class based on a variety of factors. Source

Knowing whether or not there are too few or too many students in a classroom is important when developing a methodology to determine how to educate students with individual differences. In large classes teachers may have problems with discipline and maintaining order. By reducing class sizes, educators can also reduce discipline problems. The number of students in a classroom influences the learning environment.

The most well-known and most discussed studies indicate that a classroom of around 20 students is the best class size with improvements in results of student work and teacher instruction. In classes of 20 to 40 students the results may vary with differing levels of success.
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These conclusions coincide with the studies of J. Mc Giverin, D. Gilman and C. Tillitski (1989). Their work states that in the case of second grade students in small classrooms, significantly higher test results are obtained. Scores were determined to be lower in larger classes.

Although, it seems that the classrooms with the fewest students are preferable, what really determines classroom effectiveness is the methodology used by the teachers and their attitude towards giving positive and satisfactory responses to heterogeneity and diversity in the classroom.

Many investigations have focused on the definition of an ideal class size where successful learning occurs. It is true that the effectiveness of education is not determined only by the size of the group. The importance of the size of the group is a variable that goes together with other variables to determine student success.Stated more generally, the number of students per classroom is an influential variable, but should not be considered in isolation.

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Information sources:
http://www.eldiario.es/sociedad/importancia-tener-pocos-alumnos-clase_0_670883145.html
http://www.educacionfutura.org/si-importa-el-tamano-del-grupo/