The top prize at Cannes this year went to an extraordinary film called “The Class” about a year in the life of a dedicated French high school teacher and his students, many of whom are immigrants. It is now the official French entry for the Oscars and opening in theaters across the US. I spoke to director Laurent Cantet about making the movie, which blurs the line between documentary and feature film.

Did you have a favorite teacher?

I have a few memories of some teachers who made an impression on me. I studied in school about 10 years after May 1968. Professors had also started to question their methods, and I had teachers like Francois who really tried to introduce questions, not just lectures. My parents were professors who encouraged student participation and I spent my childhood listening to people talk about school and pedagogical methods. That made an impression on me. And I have children so I see what school is like now. The French title is “Within the Walls.” I wanted to compare my experience with contemporary reality.

This film is designed to see what happens behind the scenes because school is a very private place. Children want to keep the space as a space that is theirs, their first place of independence. Professors protect themselves behind the walls of the schools.

One aspect of the school that will strike many Americans as unusual is that there are student representatives attending the faculty meetings. And indeed, the teacher in the movie finds that it creates some problems for him.

That is a requirement. It seems natural to French people to have students there, a question of honesty. There are two class representatives in staff meetings, entrusted with explaining the students point of view to professors and reporting to each student what is said about him.

What makes a great teacher?

If I knew I might be a teacher! It is indispensable that they take into account everything that the students live outside of the classroom. So the school can never seem like a sacred separate space. The world is more complex, I think, the personal stories of each of the students are more difficult, each with a very different trajectory, more than when I was in school.

The movie has elements of both documentary and fiction. It features non-professional performers and it feels very improvised, but in fact it was scripted, right?

In every movie there’s this question of reality and fiction. I like to give news, stories from the world, but I never want to do it as a thesis. I want to evaluate reality through the paths of different characters. I worked with non-professional actors who bring a way of being in front of the camera, notably they bring the experience of their own life. My job is like an orchestra leader, bringing out snippets of what they do and bringing it all together, which does not prevent me from writing a script.

What I had written was the story of Souleymane (the uncooperative boy who gets into trouble, played by Franck Keita). I met François Begaudeau (who plays Francis, the teacher), a professor for 10 years in this kind of school, who had written about little moments of classes that he had himself. It was very easy for me to offer the role to him.

We had acting workshops every Wednesday for a year, improvised with the students and he proved to me that he was terrific. We opened the workshop up to all of the students and those who stayed with it got to be in the movie.

The actress who played Souleymane’s mother was the only one who was not the real-life parent. His real mother was not in France. But as in the film does not speak French, and she did children who lived through similar situations. She created the character based upon her experiences and a way of being.

When I met her she said, “When I go to a disciplinary hearing I am going to dress myself in the most dignified way possible, like a queen.”

The boy who played Souleymane, though, in real life is the complete opposite, very nice, very laid back, almost shy. But I felt very quickly that he liked acting. I had a hard time getting him to be tough enough until we were trying on costumes. When he was dressed very differently from how he dressed in real life, he felt the character. And the goth boy is not a goth in real life either. He felt like trying out something he would not dare to do in real life, and the costume did that immediately.

There have been a lot of very high-profile movies about teachers with difficult students. What makes this one different?

Those movies were my opposite example, exactly what I wanted to avoid, to be everything except Robin Williams in “Dead Poet’s Society.” I wanted the professor to have his weakness, not to have a magic wand to solve everything. Through most of the movie we see the school can be a safe place but also a place of excluding people, like Souleymane who can’t find a place in the system but also people like Henrietta who lose interest and don’t understand what they are doing there. There is a roller coaster feeling, with great moments, great depression as much for the students as the teachers. What I want to do is describe the world in all of its complexity and contradictions.

Many thanks to translator Paul Young of Georgetown University for his assistance with this interview.