diff -u b/fapi_example/fapi_example.links.menu.yml b/fapi_example/fapi_example.links.menu.yml
--- b/fapi_example/fapi_example.links.menu.yml
+++ b/fapi_example/fapi_example.links.menu.yml
@@ -1,6 +1,6 @@
 # Define default links for this module.
 fapi_example.description:
-  title: From API Examples
+  title: Form API Examples
   description: Form examples using Drupal Form API.
   route_name: fapi_example.description
 
@@ -43,5 +43,5 @@
 fapi_example.build_demo:
   title: Build Form Demo
-  description: A form build demonstration.
+  description: Demostrates the order of firing of from controller methods.
   route_name: fapi_example.build_demo
   parent: fapi_example.description
diff -u b/fapi_example/fapi_example.routing.yml b/fapi_example/fapi_example.routing.yml
--- b/fapi_example/fapi_example.routing.yml
+++ b/fapi_example/fapi_example.routing.yml
@@ -5,8 +5,8 @@
 # controllers the content is determined by the buildForm method defined by the
 # form controller implementation.
 
-# Access to these paths is restricted to users with the permission 'access content'.
-# This is notated as _permission: 'access content'.
+# Access to these paths is restricted to users with the permission
+# 'access content'. This is notated as _permission: 'access content'.
 
 # Menu items corresponding to these URLs are defined separately in the
 # fapi_example.links.menu.yml file.
diff -u b/fapi_example/src/Form/AjaxDemo.php b/fapi_example/src/Form/AjaxDemo.php
--- b/fapi_example/src/Form/AjaxDemo.php
+++ b/fapi_example/src/Form/AjaxDemo.php
@@ -17,6 +17,11 @@
  */
 class AjaxDemo extends DemoBase {
 
+  /*
+   * Possible colors to choose from.
+   * Used by colorCallback to determine which colors to include in the
+   * select element.
+   */
   private $colors = [
     'warm' => [
       'red' => 'Red',
@@ -31,16 +36,17 @@
   ];
 
   /**
-   * Build the AJAX demo form.
-   *
-   * The #ajax attribute used in the temperature input element defines an ajax
-   * callback that will invoke the colorCallback method on this form object.
-   * Whenever the temperature element changes, it will invoke this callback and
-   * replace the contents of the color_wrapper container with the reults of this
-   * method call.
+   * {@inheritdoc}
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
 
+    /*
+     * The #ajax attribute used in the temperature input element defines an ajax
+     * callback that will invoke the colorCallback method on this form object.
+     * Whenever the temperature element changes, it will invoke this callback
+     * and replace the contents of the color_wrapper container with the reults of this
+     * method call.
+     */
     $form['temperature'] = [
       '#title' => $this->t('Temperature'),
       '#type' => 'select',
@@ -52,6 +58,8 @@
         'wrapper' => 'color-wrapper',
       ]
     ];
+
+    // Disable caching on this form.
     $form_state->setCached(FALSE);
 
     $form['actions'] =[
@@ -74,20 +82,21 @@
   }
 
   /**
-   * Getter method for Form ID.
-   *
-   * @inheritdoc
+   * {@inheritdoc}
    */
   public function getFormId() {
     return 'fapi_example_ajax_demo';
   }
 
   /**
-   * Callback for Ajax event on color selection.
+   * Implements callback for Ajax event on color selection.
    */
   public function colorCallback(array &$form, FormStateInterface $form_state) {
     $temperature = $form_state->getValue('temperature');
 
+    // Add a color element to the color_wrapper container using the value
+    // from temparature to determine which colors to include in the select
+    // element.
     $form['color_wrapper']['color'] = [
       '#type' => 'select',
       '#title' => $this->t('Color'),
diff -u b/fapi_example/src/Form/BuildDemo.php b/fapi_example/src/Form/BuildDemo.php
--- b/fapi_example/src/Form/BuildDemo.php
+++ b/fapi_example/src/Form/BuildDemo.php
@@ -15,34 +15,47 @@
  * Implements the build demo form controller.
  *
  * The form uses drupal_set_message() calls to demonstrate the order of
- * contoller method invocations by the form api.  Note that currently there is
- * no constructor in the FormBase class.
+ * contoller method invocations by the form api.
  *
  * @see \Drupal\Core\Form\FormBase
  * @see \Drupal\Core\Form\ConfigFormBase
  */
 class BuildDemo extends FormBase {
 
+  /**
+   * Counter keeping track of the sequence of method invocation.
+   * @var int
+   */
+  static $_sequence = 0;
+
+  /**
+   * {@inheritdoc}
+   */
   public function __construct() {
-    // Static variables here are used to tell you how often these methods
-    // are called within a single page load.
-    static $i=0;
-    $i++;
-    drupal_set_message("__construct $i");
+    $this->displayMethodInvocation('__contstruct');
+  }
+
+  /**
+   * Display the method being called and it's sequence in the form
+   * processing.
+   *
+   * @param $method_name
+   *   The method being invoked. 
+   */
+  private function displayMethodInvocation($method_name) {
+    self::$_sequence++;
+    drupal_set_message(self::$_sequence . ". $method_name");
   }
 
   /**
    * Build form demonstration.
    *
-   * This form demonstrates the different type of build form events and their
-   * order of firing.
+   * This form demonstrates the different type of build form methods and their
+   * order of invocation.
    */
   public function buildForm(array $form, FormStateInterface $form_state) {
 
-    static $i = 0;
-    $i++;
-    drupal_set_message("buildForm $i");
-
+    // Simple checkbox for ajax orders.
     $form['change'] = [
       '#type' => 'checkbox',
       '#title' => $this->t('Change Me'),
@@ -51,6 +64,7 @@
         'wrapper' => 'message-wrapper',
       ],
     ];
+
     $form['actions'] = [
       '#type' => 'actions',
     ];
@@ -92,64 +106,35 @@
   }
 
   /**
-   * Getter method for Form ID.
-   *
-   * The form ID is used in implementations of hook_form_alter() to allow other
-   * modules to alter the render array built by this form controller.  it must
-   * be unique site wide. It normally starts with the providing module's name.
-   *
-   * @return string
-   *   The unique ID of the form defined by this class.
+   * {@inheritdoc}
    */
   public function getFormId() {
-    static $i = 0;
-    $i++;
-    drupal_set_message("getFormId $i");
+    $this->displayMethodInvocation('getFormId');
     return 'fapi_example_simple_form';
   }
 
   /**
-   * Implements form validation.
-   *
-   * The validateForm method is the default method called to validate input on
-   * a form.
-   *
-   * @param array $form
-   *   The render array of the currently built form.
-   * @param FormStateInterface $form_state
-   *   Object describing the current state of the form.
+   * {@inheritdoc}
    */
   public function validateForm(array &$form, FormStateInterface $form_state) {
-    static $i = 0;
-    $i++;
-    drupal_set_message("validateForm $i");
+    $this->displayMethodInvocation('validateForm');
   }
 
   /**
-   * Implements a form submit handler.
-   *
-   * The submitForm method is the default method called for any submit elements.
-   *
-   * @param array $form
-   *   The render array of the currently built form.
-   * @param FormStateInterface $form_state
-   *   Object describing the current state of the form.
+   * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
-    static $i = 0;
-    $i++;
-    drupal_set_message("submitForm $i");
+    $this->displayMethodInvocation('submitForm');
   }
 
   /**
+   * Implements ajax submit callback.
+   *
    * @param array $form
    * @param \Drupal\Core\Form\FormStateInterface $form_state
-   * Demonstrates ajax button submit.
    */
   public function ajaxSubmit(array &$form, FormStateInterface $form_state) {
-    static $i = 0;
-    $i++;
-    drupal_set_message("ajaxSubmit $i");
+    $this->displayMethodInvocation('ajaxSubmit');
     $form['messages']['status'] = [
       '#type' => 'status_messages',
     ];
@@ -158,14 +143,13 @@
   }
 
   /**
+   * Implements submit callback for Rebuild button.
+   *
    * @param array $form
    * @param \Drupal\Core\Form\FormStateInterface $form_state
-   * Test a submit that causes form state rebuild
    */
   public function rebuildFormSubmit(array &$form, FormStateInterface $form_state) {
-    static $i = 0;
-    $i++;
-    drupal_set_message("rebuildFormSubmit $i");
+    $this->displayMethodInvocation('rebuildFormSubmit');
     $form_state->setRebuild(TRUE);
   }