diff --git a/README.md b/README.md
index 49f7d25..fc9b6b6 100644
--- a/README.md
+++ b/README.md
@@ -70,4 +70,25 @@ Question 2.6 :
 
 * Je génère la migration avec `rails g migration AddSizeColumnToCreatures size:integer`
 
-* `rails db:migrate`
\ No newline at end of file
+* `rails db:migrate`
+
+* J'ajoute le callback comme dans le sujet du TP pour setter la size à la création, je teste en console :
+
+```ruby
+irb(main):001:0> Creature.create(name: 'Big Chongus', health_points: 25)
+  TRANSACTION (0.1ms)  begin transaction
+  Creature Create (0.4ms)  INSERT INTO "creatures" ("name", "health_points", "created_at", "updated_at", "size") VALUES (?, ?, ?, ?, ?)  [["name", "Big Chongus"], ["health_points", 35], ["created_at", "2023-03-26 14:07:03.876318"], ["updated_at", "2023-03-26 14:07:03.876318"], ["size", 2]]
+  TRANSACTION (0.6ms)  commit transaction
+=>
+#<Creature:0x0000000109a96d70
+ id: 28,
+ name: "Big Chongus",
+ health_points: 25,
+ created_at: Sun, 26 Mar 2023 14:07:03.876318000 UTC +00:00,
+ updated_at: Sun, 26 Mar 2023 14:07:03.876318000 UTC +00:00,
+ size: "big">
+```
+
+Toutes les créatures crées auront dorénavant une taille. 
+
+
diff --git a/app/models/creature.rb b/app/models/creature.rb
index 7cc33c5..272d106 100644
--- a/app/models/creature.rb
+++ b/app/models/creature.rb
@@ -7,5 +7,14 @@ class Creature < ApplicationRecord
     "#{name} (#{health_points})"
   end
 
-
+  before_create do
+    self.size = case health_points
+      when 0..10
+        :small
+      when 11..30
+        :big
+      else
+        :giant
+    end    
+  end 
 end