4 files changed, 17 insertions, 17 deletions
diff --git a/guides/source/active_record_migrations.md b/guides/source/active_record_migrations.md
index ad069a112e..0b84001ca5 100644
--- a/guides/source/active_record_migrations.md
+++ b/guides/source/active_record_migrations.md
@@ -423,21 +423,23 @@ change_column :products, :part_number, :text
 ```
 
 This changes the column `part_number` on products table to be a `:text` field.
+Note that `change_column` command is irreversible.
 
 Besides `change_column`, the `change_column_null` and `change_column_default`
-methods are used specifically to change a not null constraint and default values of a
-column.
+methods are used specifically to change a not null constraint and default
+values of a column.
 
 ```ruby
 change_column_null :products, :name, false
-change_column_default :products, :approved, false
+change_column_default :products, :approved, from: true, to: false
 ```
 
 This sets `:name` field on products to a `NOT NULL` column and the default
-value of the `:approved` field to false.
+value of the `:approved` field from true to false.
 
-TIP: Unlike `change_column` (and `change_column_default`), `change_column_null`
-is reversible.
+Note: You could also write the above `change_column_default` migration as
+`change_column_default :products, :approved, false`, but unlike the previous
+example, this would make your migration irreversible.
 
 ### Column Modifiers
 
diff --git a/guides/source/active_support_instrumentation.md b/guides/source/active_support_instrumentation.md
index 373dbbb9aa..e49abc41f4 100644
--- a/guides/source/active_support_instrumentation.md
+++ b/guides/source/active_support_instrumentation.md
@@ -321,17 +321,6 @@ Action Mailer
 }
 ```
 
-Active Resource
---------------
-
-### request.active_resource
-
-| Key            | Value                |
-| -------------- | -------------------- |
-| `:method`      | HTTP method          |
-| `:request_uri` | Complete URI         |
-| `:result`      | HTTP response object |
-
 Active Support
 --------------
 
diff --git a/guides/source/generators.md b/guides/source/generators.md
index 14f451cbc9..32bbdc554a 100644
--- a/guides/source/generators.md
+++ b/guides/source/generators.md
@@ -503,6 +503,14 @@ Adds a specified source to `Gemfile`:
 add_source "http://gems.github.com"
 ```
 
+This method also takes a block:
+
+```ruby
+add_source "http://gems.github.com" do
+  gem "rspec-rails"
+end
+```
+
 ### `inject_into_file`
 
 Injects a block of code into a defined position in your file.
diff --git a/guides/source/getting_started.md b/guides/source/getting_started.md
index 79d4393f32..a091f84fb0 100644
--- a/guides/source/getting_started.md
+++ b/guides/source/getting_started.md
@@ -298,6 +298,7 @@ Rails.application.routes.draw do
 
   # The priority is based upon order of creation:
   # first created -> highest priority.
+  # See how all your routes lay out with "rake routes".
   #
   # You can have the root of your site routed with "root"
   # root 'welcome#index'