France, June 1 -- Half of France's regional languages are considered 'seriously endangered' according to Unesco, but in the west of the country, where the decline in Breton speakers has accelerated in recent years, a network of schools is fighting the decline.

"Demat!" Greetings echo through the corridors of the Diwan secondary school in Vannes. In the entrance hall, Gabriella and her classmates are filling a whiteboard with words of farewell and thanks - "kenavo" and "trugarez" - for someone who is leaving.

Here, with the exception of French and the foreign languages taught, the 145 secondary school pupils and 45 high school students take all their lessons in Breton, and the use of thelanguage is strongly encouraged during breaks, at l...