Most of the following activities are linked to the association Animath; I am a member of its executive board.
French olympiad training program (POFM)
Since 2013, I am a teacher and organizer in the French preparation for the International Mathematical Olympiad. We organize camps in August, October and February, as well as distance training and several tests throughout the year. In Spring, we select students for various international competitions (including the IMO, the EGMO, the JBMO and the MYMC).
Also, I taught combinatorics during the Winter camp 2017 of the Moroccan training program.
French Tournament for Young Mathematicians (TFJM^2)
This tournament aims at introducing high school students to mathematical research: teams of six students (lead by two teachers) have three months to search open problems (with easy questions at the beginning). During the contest, each team has to present its results in debates with the other teams, in front of a jury. Despite the competitive side, the discussions are lead in a cordial manner, as a goal of the event is to foster cooperation and exchanges between math fans. The winning teams are invited to the international tournament.
Many problems are engaging to search (often about discrete optimization and combinatorics), since they are open while young students can tackle them. Annals are here (only in French).
I was participant in 2011, team leader in 2012 and 2014, jury member from 2012 to 2018 and member of the problem selection committee from 2015 to 2018.
Every Saturday in Paris, this math club for high school students proposes sessions of maths that are usually not taught at school.
I was its organizer in 2015-2016 and gave several sessions between 2014 and 2017.