According to daily Le Matin, the trio had no idea they would get in hot water when they launched the site and thought it would be a useful tool for the public.
Speaking to the paper, pupil Nathan Ganser, who founded the site with two friends, said: “Teachers assess their students, so this project was an opportunity for us to do the same.”
Less than two days after they started the site, 600 out of the school's 1,300 pupils had posted their opinions on their teachers, and the trio had received support from many students and even some parents, said the paper.
They even wanted to extend the site to other schools.
But teachers were not impressed, and have suspended the trio for three weeks.
“Students do not have the authority to evaluate their teachers,” the school's head Véronique Mariani told Le Matin, adding that they “ignored warnings”.
The president of a headteachers' association in Vaud, Francoise Emmanuelle Nicolet, agreed with the school's stance.
“The content of the site doesn't meet legal standards,” she said, adding that the public nature of the site could lead to teachers' images being tainted or even their disqualification.