diff --git a/lib/PHPPeru/Exam/ExamInterface.php b/lib/PHPPeru/Exam/ExamInterface.php
index 419b077..5523f05 100644
--- a/lib/PHPPeru/Exam/ExamInterface.php
+++ b/lib/PHPPeru/Exam/ExamInterface.php
@@ -1,35 +1,35 @@
-<?php
-namespace PHPPeru\Exam;
-
-use Symfony\Component\EventDispatcher\EventDispatcherInterface,
-    BadMethodCallException;
-
-/**
- * Descrobes a minimal API required for the concept of Exam
- *
- * @author Marco Pivetta <ocramius@gmail.com>
- * @todo add methods to the interface besides the ones used as examples
- */
-interface ExamInterface
-{    
-    /**
-     * Begins the exam.
-     * 
-     * @throws BadMethodCallException if the exam can't be started 
-     */
-    public function start();
-    
-    /**
-     * Aborts the exam.
-     * 
-     * @throws BadMethodCallException if the exam can't be aborted 
-     */
-    public function abort();
-    
-    /**
-     * Completes the exam
-     *
-     * @throws BadMethodCallException if the exam can't be completed 
-     */
-    public function complete();
+<?php
+namespace PHPPeru\Exam;
+
+use Symfony\Component\EventDispatcher\EventDispatcherInterface,
+    BadMethodCallException;
+
+/**
+ * Descrobes a minimal API required for the concept of Exam
+ *
+ * @author Marco Pivetta <ocramius@gmail.com>
+ * @todo add methods to the interface besides the ones used as examples
+ */
+interface ExamInterface extends Iterator
+{    
+    /**
+     * Begins the exam.
+     * 
+     * @throws BadMethodCallException if the exam can't be started 
+     */
+    public function start();
+    
+    /**
+     * Aborts the exam.
+     * 
+     * @throws BadMethodCallException if the exam can't be aborted 
+     */
+    public function abort();
+    
+    /**
+     * Completes the exam
+     *
+     * @throws BadMethodCallException if the exam can't be completed 
+     */
+    public function complete();
 }
\ No newline at end of file
diff --git a/lib/PHPPeru/Exam/SimpleExam.php b/lib/PHPPeru/Exam/SimpleExam.php
index a2cdf0c..82ca9e5 100644
--- a/lib/PHPPeru/Exam/SimpleExam.php
+++ b/lib/PHPPeru/Exam/SimpleExam.php
@@ -1,134 +1,169 @@
-<?php
-namespace PHPPeru\Exam;
-
-use Symfony\Component\EventDispatcher\EventDispatcherInterface,
-    Symfony\Component\EventDispatcher\EventDispatcher,
-    BadMethodCallException;
-
-/**
- * Provides a simple concrete exam object that is able to trigger events during
- * its lifecycle.
- *
- * @author Marco Pivetta <ocramius@gmail.com>
- * @todo eventually define if ".pre" or ".post" events should be used.
- */
-class SimpleExam implements ExamInterface
-{
-    
-    const STATUS_NEW        = 0;
-    const STATUS_STARTED    = 1;
-    const STATUS_ABORTED    = 2;
-    const STATUS_COMPLETED  = 4;
-    
-    const EVENT_START       = 'start';
-    const EVENT_ABORT       = 'abort';
-    const EVENT_COMPLETE    = 'complete';
-
-    /**
-     * Event dispatcher used internally to trigger events during lifecycle
-     *
-     * @var EventDispatcherInterface
-     */
-    protected $eventDispatcher;
-    
-    /**
-     * Defines the current status of the exam
-     *
-     * @var type 
-     */
-    protected $status = self::STATUS_NEW;
-    
-    /**
-     * Default constructor, initializes events 
-     */
-    public function __construct()
-    {
-        $this->eventDispatcher = new EventDispatcher();
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function start()
-    {
-        if (!$this->isNew()) {
-            throw new BadMethodCallException('Exam is not new');
-        }
-        $this->status = self::STATUS_STARTED;
-        $this->eventDispatcher->dispatch(self::EVENT_START, new Event($this));
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function abort()
-    {
-        if (!$this->isStarted()) {
-            throw new BadMethodCallException('Exam is not started');
-        }
-        $this->status = self::STATUS_ABORTED;
-        $this->eventDispatcher->dispatch(self::EVENT_ABORT, new Event($this));
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function complete()
-    {
-        if (!$this->isStarted()) {
-            throw new BadMethodCallException('Exam is not started');
-        }
-        $this->status = self::STATUS_COMPLETED;
-        $this->eventDispatcher->dispatch(self::EVENT_COMPLETE, new Event($this));
-    }
-
-    /**
-     * Checks if the exam is new
-     *
-     * @return bool 
-     */
-    public function isNew()
-    {
-        return $this->status === self::STATUS_NEW;
-    }
-
-    /**
-     * Checks if the exam has been started
-     *
-     * @return bool 
-     */
-    public function isStarted()
-    {
-        return $this->status === self::STATUS_STARTED;
-    }
-
-    /**
-     * Checks if the exam has been aborted
-     *
-     * @return bool 
-     */
-    public function isAborted()
-    {
-        return $this->status === self::STATUS_ABORTED;
-    }
-
-    /**
-     * Checks if the exam has been completed
-     *
-     * @return bool 
-     */
-    public function isCompleted()
-    {
-        return $this->status === self::STATUS_COMPLETED;
-    }
-    
-    /**
-     * Retrieves the associated event dispatcher
-     *
-     * @return EventDispatcherInterface 
-     */
-    public function getEventDispatcher()
-    {
-        return $this->eventDispatcher;
-    }
+<?php
+namespace PHPPeru\Exam;
+
+use Symfony\Component\EventDispatcher\EventDispatcherInterface,
+    Symfony\Component\EventDispatcher\EventDispatcher,
+    BadMethodCallException;
+
+/**
+ * Provides a simple concrete exam object that is able to trigger events during
+ * its lifecycle.
+ *
+ * @author Marco Pivetta <ocramius@gmail.com>
+ * @todo eventually define if ".pre" or ".post" events should be used.
+ */
+class SimpleExam implements ExamInterface
+{
+    
+    const STATUS_NEW        = 0;
+    const STATUS_STARTED    = 1;
+    const STATUS_ABORTED    = 2;
+    const STATUS_COMPLETED  = 4;
+    
+    const EVENT_START       = 'start';
+    const EVENT_ABORT       = 'abort';
+    const EVENT_COMPLETE    = 'complete';
+
+    /**
+     * Event dispatcher used internally to trigger events during lifecycle
+     *
+     * @var EventDispatcherInterface
+     */
+    protected $eventDispatcher;
+    
+    /**
+     * Defines the current status of the exam
+     *
+     * @var type 
+     */
+    protected $status = self::STATUS_NEW;
+    
+    /**
+     * Default constructor, initializes events 
+     */
+    public function __construct()
+    {
+        $this->eventDispatcher = new EventDispatcher();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function start()
+    {
+        if (!$this->isNew()) {
+            throw new BadMethodCallException('Exam is not new');
+        }
+        $this->status = self::STATUS_STARTED;
+        $this->eventDispatcher->dispatch(self::EVENT_START, new Event($this));
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function abort()
+    {
+        if (!$this->isStarted()) {
+            throw new BadMethodCallException('Exam is not started');
+        }
+        $this->status = self::STATUS_ABORTED;
+        $this->eventDispatcher->dispatch(self::EVENT_ABORT, new Event($this));
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function complete()
+    {
+        if (!$this->isStarted()) {
+            throw new BadMethodCallException('Exam is not started');
+        }
+        $this->status = self::STATUS_COMPLETED;
+        $this->eventDispatcher->dispatch(self::EVENT_COMPLETE, new Event($this));
+    }
+
+    /**
+     * Checks if the exam is new
+     *
+     * @return bool 
+     */
+    public function isNew()
+    {
+        return $this->status === self::STATUS_NEW;
+    }
+
+    /**
+     * Checks if the exam has been started
+     *
+     * @return bool 
+     */
+    public function isStarted()
+    {
+        return $this->status === self::STATUS_STARTED;
+    }
+
+    /**
+     * Checks if the exam has been aborted
+     *
+     * @return bool 
+     */
+    public function isAborted()
+    {
+        return $this->status === self::STATUS_ABORTED;
+    }
+
+    /**
+     * Checks if the exam has been completed
+     *
+     * @return bool 
+     */
+    public function isCompleted()
+    {
+        return $this->status === self::STATUS_COMPLETED;
+    }
+    
+    /**
+     * Retrieves the associated event dispatcher
+     *
+     * @return EventDispatcherInterface 
+     */
+    public function getEventDispatcher()
+    {
+        return $this->eventDispatcher;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function current() {
+        throw new BadMethodCallException('Not implemented');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function key() {
+        throw new BadMethodCallException('Not implemented');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function next() {
+        throw new BadMethodCallException('Not implemented');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function rewind() {
+        throw new BadMethodCallException('Not implemented');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function valid() {
+        throw new BadMethodCallException('Not implemented');
+    }
 }
\ No newline at end of file