1 files changed, 4 insertions, 2 deletions
diff --git a/activemodel/lib/active_model/observing.rb b/activemodel/lib/active_model/observing.rb
index b905d2b6d2..a6b6dfafe7 100644
--- a/activemodel/lib/active_model/observing.rb
+++ b/activemodel/lib/active_model/observing.rb
@@ -70,8 +70,8 @@ module ActiveModel
       end
 
       # Notify list of observers of a change.
-      def notify_observers(*arg)
-        observer_instances.each { |observer| observer.update(*arg) }
+      def notify_observers(*args)
+        observer_instances.each { |observer| observer.update(*args) }
       end
 
       # Total number of observers.
@@ -221,6 +221,7 @@ module ActiveModel
     end
 
     # Start observing the declared classes and their subclasses.
+    # Called automatically by the instance method.
     def initialize
       observed_classes.each { |klass| add_observer!(klass) }
     end
@@ -249,6 +250,7 @@ module ActiveModel
         klass.add_observer(self)
       end
 
+      # Returns true if notifications are disabled for this object.
       def disabled_for?(object)
         klass = object.class
         return false unless klass.respond_to?(:observers)