Update textbook.en.md

brainstorming-innovative-courses/textbook.en.md

@@ -21,7 +21,7 @@ Here are for example some big "concepts" that we could call for example "big ide
 
 
 If this is an idea that seems interesting to you, we could think collectively to structure a little these "big ideas" (for example what would be the big ideas really transverse
-to all our physics lessons from beginning of bachelor/licence to end of master) and intelligible to a high school student. Then pick one as a try to see what it gives. "
+to all our physics lessons from beginning of bachelor/licence to end of master) and intelligible to a high school student. We can create a fifth (even sixth) level for the master, which would not be "online", but could be shared (or not) by the partner institutes and their students. Then pick one as a try to see what it gives. "
 I think myself of new "big concept" that I put here: