ENS Lyon, Monod site
There are two sites for ENS Lyon, Descartes and Monod, you have to go to the Monod site, the address is 46 allée d'Italie.
From the city center, take the B line towards Gare d'Oullins, exit at Debourg station. There are two exits, choose the one at the front of the train. Walk straight until the next crossroad (you'll have a pharmacy on your left), turn right, cross the road, and go straight (in Rue Challemel Lacour): you will reach Place des Pavillons. Continue straight ahead, which involves crossing the "square", you will reach allee d'Italie in front of you.
The ENS Lyon, Monod site looks like this:
the welcome desk is under the "bridge", to your left.
Ring the bell and give your name to the people at the welcome desk, they will direct you to the third floor, to the MSC/Chocola meeting.