Sure Émilie, go to your local market and buy an inexpensive bottle of wine, a baguette, brie cheese, and enjoy yourself. This is one of my favorite things to do in France.
However, for your moodle question, you will probably need to tell us what you are really trying to do, and what problems you have encountered.
I have been using Moodle's group feature for forums. I break my class into groups of 10-15 students. When I create a new post, I make sure to click on the button to send this post to all groups. Then, as I participate in each group topic, any post that I make goes out to only the group members. If I make a new post (outside of a group), it goes to everyone. I am in as the Manager role (I run a small moodle), but I would think that this works the same for the Teacher role. I have never tried it, but if you put a teacher into a group, I wonder if this teacher will only be able to see the students in their group. I would test this before implementation.