diff --git a/grade/grading/form/guide/lib.php b/grade/grading/form/guide/lib.php
index 8199efa6bef..3565ef60734 100644
--- a/grade/grading/form/guide/lib.php
+++ b/grade/grading/form/guide/lib.php
@@ -756,6 +756,26 @@ class gradingform_guide_instance extends gradingform_instance {
         return $instanceid;
     }
 
+    /**
+     * Determines whether the submitted form was empty.
+     *
+     * @param array $elementvalue value of element submitted from the form
+     * @return boolean true if the form is empty
+     */
+    public function is_empty_form($elementvalue) {
+        $criteria = $this->get_controller()->get_definition()->guide_criteria;
+        foreach ($criteria as $id => $criterion) {
+            $score = $elementvalue['criteria'][$id]['score'];
+            $remark = $elementvalue['criteria'][$id]['remark'];
+
+            if ((isset($score) && $score !== '')
+                    || ((isset($remark) && $remark !== ''))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /**
      * Validates that guide is fully completed and contains valid grade on each criterion
      *
@@ -843,6 +863,19 @@ class gradingform_guide_instance extends gradingform_instance {
         $this->get_guide_filling(true);
     }
 
+    /**
+     * Removes the attempt from the gradingform_guide_fillings table
+     * @param array $data the attempt data
+     */
+    public function clear_attempt($data) {
+        global $DB;
+
+        foreach ($data['criteria'] as $criterionid => $record) {
+            $DB->delete_records('gradingform_guide_fillings',
+                array('criterionid' => $criterionid, 'instanceid' => $this->get_id()));
+        }
+    }
+
     /**
      * Calculates the grade to be pushed to the gradebook
      *
diff --git a/grade/grading/form/lib.php b/grade/grading/form/lib.php
index 6e926d58a25..b79f5c77362 100644
--- a/grade/grading/form/lib.php
+++ b/grade/grading/form/lib.php
@@ -935,6 +935,28 @@ abstract class gradingform_instance {
      */
     abstract public function get_grade();
 
+    /**
+     * Determines whether the submitted form was empty.
+     *
+     * @param array $elementvalue value of element submitted from the form
+     * @return boolean true if the form is empty
+     */
+    public function is_empty_form($elementvalue) {
+        return false;
+    }
+
+    /**
+     * Removes the attempt from the gradingform_*_fillings table.
+     * This function is not abstract as to not break plugins that might
+     * use advanced grading.
+     * @param array $data the attempt data
+     */
+    public function clear_attempt($data) {
+        // This function is empty because the way to clear a grade
+        // attempt will be different depending on the grading method.
+        return;
+    }
+
     /**
      * Called when teacher submits the grading form:
      * updates the instance in DB, marks it as ACTIVE and returns the grade to be pushed to the gradebook.
@@ -947,12 +969,16 @@ abstract class gradingform_instance {
      */
     public function submit_and_get_grade($elementvalue, $itemid) {
         $elementvalue['itemid'] = $itemid;
+        if ($this->is_empty_form($elementvalue)) {
+            $this->clear_attempt($elementvalue);
+            $this->make_active();
+            return -1;
+        }
         $this->update($elementvalue);
         $this->make_active();
         return $this->get_grade();
     }
 
-
     /**
      * Returns html for form element of type 'grading'. If there is a form input element
      * it must have the name $gradingformelement->getName().
diff --git a/grade/grading/form/rubric/lib.php b/grade/grading/form/rubric/lib.php
index 36d366d9ed3..d4d4b6f8c15 100644
--- a/grade/grading/form/rubric/lib.php
+++ b/grade/grading/form/rubric/lib.php
@@ -756,6 +756,37 @@ class gradingform_rubric_instance extends gradingform_instance {
         return $instanceid;
     }
 
+    /**
+     * Determines whether the submitted form was empty.
+     *
+     * @param array $elementvalue value of element submitted from the form
+     * @return boolean true if the form is empty
+     */
+    public function is_empty_form($elementvalue) {
+        $criteria = $this->get_controller()->get_definition()->rubric_criteria;
+
+        foreach ($criteria as $id => $criterion) {
+            if (isset($elementvalue['criteria'][$id]['levelid'])
+                    || !empty($elementvalue['criteria'][$id]['remark'])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Removes the attempt from the gradingform_guide_fillings table
+     * @param array $data the attempt data
+     */
+    public function clear_attempt($data) {
+        global $DB;
+
+        foreach ($data['criteria'] as $criterionid => $record) {
+            $DB->delete_records('gradingform_rubric_fillings',
+                array('criterionid' => $criterionid, 'instanceid' => $this->get_id()));
+        }
+    }
+
     /**
      * Validates that rubric is fully completed and contains valid grade on each criterion
      *
diff --git a/lib/form/grading.php b/lib/form/grading.php
index 00674218849..18191dd6d40 100644
--- a/lib/form/grading.php
+++ b/lib/form/grading.php
@@ -138,11 +138,14 @@ class MoodleQuickForm_grading extends HTML_QuickForm_input{
      * Function registered as rule for this element and is called when this element is being validated.
      * This is a wrapper to pass the validation to the method gradingform_instance::validate_grading_element
      *
-     * @param mixed $elementValue value of element to be validated
+     * @param mixed $elementvalue value of element to be validated
      * @param array $attributes element attributes
      * @return MoodleQuickForm_grading
      */
-    static function _validate($elementValue, $attributes = null) {
-        return $attributes['gradinginstance']->validate_grading_element($elementValue);
+    public static function _validate($elementvalue, $attributes = null) {
+        if (!$attributes['gradinginstance']->is_empty_form($elementvalue)) {
+            return $attributes['gradinginstance']->validate_grading_element($elementvalue);
+        }
+        return true;
     }
 }