Teachers in Paris and western France have begun giving every pupil in their classes top marks in tests and evaluations in protest at changes to France’s baccalaureate exams.

The baccalaureate, which pupils take in their last year of high school, is based on a structure created under Napoleon in 1808. A revamp of the education system by the president, Emmanuel Macron, has been presented as key to his pro-business project to modernise the French economy.

From next year, students will begin preparing for a new exam system. The number of tests in the baccalaureate will be reduced and adapted, with new specialisms in topics that will lead students towards specific university degrees sooner.

A previous rightwing government that attempted similar changes was stopped by street demonstrations but Macron’s revamp is going ahead despite pupils blockading schools in protest.

Some teachers said it could deepen inequalities in an education system where social background already has a big impact on pupils’ chances of success.

A teacher at the Lycée Sophie Germain in Paris told France Inter radio that school heads and education bodies relied on a hierarchy of grades for students. “With this protest action, we can block the administrative system,” they said.

A pupil at the school said: “The French education system really cares about grades, so playing on that might work. If we all have 20/20. Something is going to have to be done.”

In the western city of Nantes, some teachers have also given full marks to the whole class. “We mark the work and tell pupils their real grades,” one teacher told the local paper Ouest France, but added that on the school’s internal grading software system, “we put in 20/20 for everyone”.

The government said the teachers opposing the revamp were in a minority. The largest union for high school directors approves the planned new system.

The Élysée Palace lists Macron’s changes to the education system, including halving certain primary class sizes in deprived areas, as among his biggest achievements. The education minister, Jean-Michel Blanquer, who was an education adviser under the government of Nicolas Sarkozy, was asked if he was reactionary because of his plans to place a French flag in every classroom. He said he was not and that civic education in schools was crucial.

Macron has argued that the baccalaureate is failing to adequately prepare teenagers for university and the modern job market.

The government has also introduced a system of more selective entry requirements for university, which prompted students to blockade university buildings last year.

Pupils protesting against changes to exams and university entrance blockaded high-schools during the gilets jaunes anti-government demonstrations in November and December, leading to clashes with police.