diff --git a/00.brainstorming-pedagogical-teams/45.synthesis-structuring/electromagnetism/n1/textbook.en.md b/00.brainstorming-pedagogical-teams/45.synthesis-structuring/electromagnetism/n1/textbook.en.md
index 7e538c28c..08e3026f4 100644
--- a/00.brainstorming-pedagogical-teams/45.synthesis-structuring/electromagnetism/n1/textbook.en.md
+++ b/00.brainstorming-pedagogical-teams/45.synthesis-structuring/electromagnetism/n1/textbook.en.md
@@ -10,5 +10,6 @@ lessons:
 
 #### Brainstorming to structure a theme "Electromagnetism" : level 1
 
---------------------------------
-
+This step is important, because it will be the 
+**first tree structure of the filesystems and subfiles in which the contributors will work**. 
+This tree structure may evolve, but it is less agile than the pedagi
\ No newline at end of file