Is it important for children to be taught by teachers of both sexes ?

Education is a debate [that is] very important in our society. In fact, in the 20th century, there were more women who [whose implies possession] are teachers than men. But, nowadays, male teachers impose [maybe instead of impose, dominate] in the sector of the education. This difference is more common in primary school than other school [school age? other school implies a specific school, rather than an age group]. But, is it important for children to be taught by teachers of both sexes? Or, [new sentence, a question mark is like a period in that it says that the sentence has ended] the fact that women teachers are more numerous don’t [doesn't] pose any problem for [no the] children’s development? First, I will show the disadvantages of [no the, and female instead of women sounds better] women teachers. And, secondly, I will show the advantages of male teachers.

First of all, teachers of both sexes are necessary for children. Indeed, we can see that women teachers are [the] majority in the sector of the education. However, what can reproach in the education of women is that they [are] maternal [to] their student[s]. They aren’t really a model for children, but more a second mother. In fact, women teachers are less autoritative than men. For example, when a child do [does, third person singular] something wrong, they [are, going is present progressive and you still need the verb "to be"] going to look at understand the child but without punishing her/him necessarily. They highlight their maternal instinct and not their role of [a] teacher [role is the subject, so not all teachers, but the generic role of a teacher]. That is why, male teachers are less numerous, because they don’t have this problem of maternal instinct.

Then, even if male teacher are [the, minority is singular, so you put the in front] minority, we can see many advantages. In fact, the problem is situated in the families of students. At most time [Most of the time is a more natural way to express this idea], in a family, the mother takes care of their children, when the father is working, for instance. As a consequence, children need a male model and an example of authority in their life, especially for young boys. As a matter of fact, with the authority of the male teacher, children can understand that school is an authority place. Male teachers are not maternal. [Or, if you want to stick with singular, A male teacher is not maternal.]

All things considered, we can say that is very important for children to be taught by teacher of both sexes. In fact, children need a model of women and men in the sector of education for their development.

Nice job, those were some complicated thoughts and you expressed them well! Just a little tidying up of the grammar and vocabulary. If you want to learn more, we can have some classes together!