1 files changed, 22 insertions, 11 deletions
diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md
index 26d9a86be0..455dc7bebe 100644
--- a/guides/source/form_helpers.md
+++ b/guides/source/form_helpers.md
@@ -342,7 +342,7 @@ If you have created namespaced routes, `form_for` has a nifty shorthand for that
 form_for [:admin, @article]
 ```
 
-will create a form that submits to the articles controller inside the admin namespace (submitting to `admin_article_path(@article)` in the case of an update). If you have several levels of namespacing then the syntax is similar:
+will create a form that submits to the `ArticlesController` inside the admin namespace (submitting to `admin_article_path(@article)` in the case of an update). If you have several levels of namespacing then the syntax is similar:
 
 ```ruby
 form_for [:admin, :management, @article]
@@ -751,7 +751,7 @@ You might want to render a form with a set of edit fields for each of a person's
 <%= form_for @person do |person_form| %>
   <%= person_form.text_field :name %>
   <% @person.addresses.each do |address| %>
-    <%= person_form.fields_for address, index: address do |address_form|%>
+    <%= person_form.fields_for address, index: address.id do |address_form|%>
       <%= address_form.text_field :city %>
     <% end %>
   <% end %>
@@ -774,9 +774,16 @@ This will result in a `params` hash that looks like
 {'person' => {'name' => 'Bob', 'address' => {'23' => {'city' => 'Paris'}, '45' => {'city' => 'London'}}}}
 ```
 
-Rails knows that all these inputs should be part of the person hash because you called `fields_for` on the first form builder. By specifying an `:index` option you're telling Rails that instead of naming the inputs `person[address][city]` it should insert that index surrounded by [] between the address and the city. If you pass an Active Record object as we did then Rails will call `to_param` on it, which by default returns the database id. This is often useful as it is then easy to locate which Address record should be modified. You can pass numbers with some other significance, strings or even `nil` (which will result in an array parameter being created).
+Rails knows that all these inputs should be part of the person hash because you
+called `fields_for` on the first form builder. By specifying an `:index` option
+you're telling Rails that instead of naming the inputs `person[address][city]`
+it should insert that index surrounded by [] between the address and the city.
+This is often useful as it is then easy to locate which Address record
+should be modified. You can pass numbers with some other significance,
+strings or even `nil` (which will result in an array parameter being created).
 
-To create more intricate nestings, you can specify the first part of the input name (`person[address]` in the previous example) explicitly, for example
+To create more intricate nestings, you can specify the first part of the input
+name (`person[address]` in the previous example) explicitly:
 
 ```erb
 <%= fields_for 'person[address][primary]', address, index: address do |address_form| %>
@@ -859,7 +866,7 @@ end
 
 This creates an `addresses_attributes=` method on `Person` that allows you to create, update and (optionally) destroy addresses.
 
-### Building the Form
+### Nested Forms
 
 The following form allows a user to create a `Person` and its associated addresses.
 
@@ -882,16 +889,18 @@ The following form allows a user to create a `Person` and its associated address
 ```
 
 
-When an association accepts nested attributes `fields_for` renders its block once for every element of the association. In particular, if a person has no addresses it renders nothing. A common pattern is for the controller to build one or more empty children so that at least one set of fields is shown to the user. The example below would result in 3 sets of address fields being rendered on the new person form.
+When an association accepts nested attributes `fields_for` renders its block once for every element of the association. In particular, if a person has no addresses it renders nothing. A common pattern is for the controller to build one or more empty children so that at least one set of fields is shown to the user. The example below would result in 2 sets of address fields being rendered on the new person form.
 
 ```ruby
 def new
   @person = Person.new
-  3.times { @person.addresses.build}
+  2.times { @person.addresses.build}
 end
 ```
 
-`fields_for` yields a form builder that names parameters in the format expected the accessor generated by `accepts_nested_attributes_for`. For example when creating a user with 2 addresses, the submitted parameters would look like
+The `fields_for` yields a form builder. The parameters' name will be what
+`accepts_nested_attributes_for` expects. For example when creating a user with
+2 addresses, the submitted parameters would look like:
 
 ```ruby
 {
@@ -913,7 +922,7 @@ end
 
 The keys of the `:addresses_attributes` hash are unimportant, they need merely be different for each address.
 
-If the associated object is already saved, `fields_for` autogenerates a hidden input with the `id` of the saved record. You can disable this by passing `include_id: false` to `fields_for`. You may wish to do this if the autogenerated input is placed in a location where an input tag is not valid HTML or when using an ORM where children do not have an id.
+If the associated object is already saved, `fields_for` autogenerates a hidden input with the `id` of the saved record. You can disable this by passing `include_id: false` to `fields_for`. You may wish to do this if the autogenerated input is placed in a location where an input tag is not valid HTML or when using an ORM where children do not have an `id`.
 
 ### The Controller
 
@@ -944,7 +953,9 @@ class Person < ActiveRecord::Base
 end
 ```
 
-If the hash of attributes for an object contains the key `_destroy` with a value of '1' or 'true' then the object will be destroyed. This form allows users to remove addresses:
+If the hash of attributes for an object contains the key `_destroy` with a value
+of `1` or `true` then the object will be destroyed. This form allows users to
+remove addresses:
 
 ```erb
 <%= form_for @person do |f| %>
@@ -952,7 +963,7 @@ If the hash of attributes for an object contains the key `_destroy` with a value
   <ul>
     <%= f.fields_for :addresses do |addresses_form| %>
       <li>
-        <%= check_box :_destroy%>
+        <%= addresses_form.check_box :_destroy%>
         <%= addresses_form.label :kind %>
         <%= addresses_form.text_field :kind %>
         ...