diff --git a/grade/edit/tree/category.php b/grade/edit/tree/category.php
index 81915da0447..a0cbf5f3b1b 100644
--- a/grade/edit/tree/category.php
+++ b/grade/edit/tree/category.php
@@ -58,7 +58,13 @@ if ($id) {
     // set parent
     $category->parentcategory = $grade_category->parent;
     $grade_item = $grade_category->load_grade_item();
-    foreach ($grade_item as $key => $value) {
+    // nomalize coef values if needed
+    if ($parent_category = $grade_category->get_parent_category()) {
+        if ($parent_category->aggregation == GRADE_AGGREGATE_SUM or $parent_category->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN2) {
+            $grade_item->aggregationcoef = $grade_item->aggregationcoef == 0 ? 0 : 1;
+        }
+    }
+    foreach ($grade_item->get_record_data() as $key => $value) {
         $category->{"grade_item_$key"} = $value;
     }
 
diff --git a/grade/edit/tree/item.php b/grade/edit/tree/item.php
index ef0bf354543..cacf6aa6857 100644
--- a/grade/edit/tree/item.php
+++ b/grade/edit/tree/item.php
@@ -96,8 +96,8 @@ $item->plusfactor      = format_float($item->plusfactor, 4);
 
 if (empty($parent_category)) {
     $item->aggregationcoef = 0;
-} else if ($parent_category->aggregation == GRADE_AGGREGATE_SUM) {
-    $item->aggregationcoef = $item->aggregationcoef > 0 ? 1 : 0;
+} else if ($parent_category->aggregation == GRADE_AGGREGATE_SUM or $parent_category->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN2) {
+    $item->aggregationcoef = $item->aggregationcoef == 0 ? 0 : 1;
 } else {
     $item->aggregationcoef = format_float($item->aggregationcoef, 4);
 }
diff --git a/grade/edit/tree/lib.php b/grade/edit/tree/lib.php
index 2ff1dca05b4..fc201092187 100755
--- a/grade/edit/tree/lib.php
+++ b/grade/edit/tree/lib.php
@@ -566,7 +566,7 @@ class grade_edit_tree_column_aggregation extends grade_edit_tree_column_category
         }
 
         $script = "window.location='index.php?id={$params['id']}&category={$category->id}&aggregationtype='+this.value+'&sesskey=" . sesskey()."';";
-        $aggregation = choose_from_menu($options, 'aggregation_'.$category->id, $category->aggregation, get_string('choose'), $script, 0, true);
+        $aggregation = choose_from_menu($options, 'aggregation_'.$category->id, $category->aggregation, null, $script, 0, true);
 
         if ($this->forced) {
             $aggregation = $options[$category->aggregation];
diff --git a/grade/edit/tree/outcomeitem_form.php b/grade/edit/tree/outcomeitem_form.php
index 3fbb0dbb8a1..0cbea5b05e4 100644
--- a/grade/edit/tree/outcomeitem_form.php
+++ b/grade/edit/tree/outcomeitem_form.php
@@ -102,6 +102,9 @@ class edit_outcomeitem_form extends moodleform {
                 if ($cat->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN) {
                     $coefstring = ($coefstring=='' or $coefstring=='aggregationcoefweight') ? 'aggregationcoefweight' : 'aggregationcoef';
 
+                } else if ($cat->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN2) {
+                    $coefstring = ($coefstring=='' or $coefstring=='aggregationcoefextrasum') ? 'aggregationcoefextrasum' : 'aggregationcoef';
+
                 } else if ($cat->aggregation == GRADE_AGGREGATE_EXTRACREDIT_MEAN) {
                     $coefstring = ($coefstring=='' or $coefstring=='aggregationcoefextra') ? 'aggregationcoefextra' : 'aggregationcoef';
 
@@ -201,6 +204,9 @@ class edit_outcomeitem_form extends moodleform {
                     if ($parent_category->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN) {
                         $aggcoef = 'aggregationcoefweight';
 
+                    } else if ($parent_category->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN2) {
+                        $aggcoef = 'aggregationcoefextrasum';
+
                     } else if ($parent_category->aggregation == GRADE_AGGREGATE_EXTRACREDIT_MEAN) {
                         $aggcoef = 'aggregationcoefextra';
 
diff --git a/lib/grade/grade_category.php b/lib/grade/grade_category.php
index 041be4d49c3..20b03f3a329 100644
--- a/lib/grade/grade_category.php
+++ b/lib/grade/grade_category.php
@@ -642,19 +642,23 @@ class grade_category extends grade_object {
                 }
                 break;
 
-            case GRADE_AGGREGATE_WEIGHTED_MEAN2: // Weighted average of all existing final grades, weight is the range of grade (ususally grademax)
+            case GRADE_AGGREGATE_WEIGHTED_MEAN2:
+                // Weighted average of all existing final grades with optional extra credit flag,
+                // weight is the range of grade (ususally grademax)
                 $weightsum = 0;
-                $sum       = 0;
+                $sum       = null;
                 foreach($grade_values as $itemid=>$grade_value) {
                     $weight = $items[$itemid]->grademax - $items[$itemid]->grademin;
                     if ($weight <= 0) {
                         continue;
                     }
-                    $weightsum += $weight;
-                    $sum       += $weight * $grade_value;
+                    if ($items[$itemid]->aggregationcoef == 0) {
+                        $weightsum += $weight;
+                    }
+                    $sum += $weight * $grade_value;
                 }
                 if ($weightsum == 0) {
-                    $agg_grade = null;
+                    $agg_grade = $sum; // only extra credits
                 } else {
                     $agg_grade = $sum / $weightsum;
                 }
@@ -662,7 +666,7 @@ class grade_category extends grade_object {
 
             case GRADE_AGGREGATE_EXTRACREDIT_MEAN: // special average
                 $num = 0;
-                $sum = 0;
+                $sum = null;
                 foreach($grade_values as $itemid=>$grade_value) {
                     if ($items[$itemid]->aggregationcoef == 0) {
                         $num += 1;
@@ -806,6 +810,7 @@ class grade_category extends grade_object {
      */
     function is_aggregationcoef_used() {
         return ($this->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN
+             or $this->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN2
              or $this->aggregation == GRADE_AGGREGATE_EXTRACREDIT_MEAN
              or $this->aggregation == GRADE_AGGREGATE_SUM);
 
@@ -847,6 +852,8 @@ class grade_category extends grade_object {
         // No parent category is overriding this category's aggregation, return its string
         if ($this->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN) {
             $this->coefstring = 'aggregationcoefweight';
+        } else if ($this->aggregation == GRADE_AGGREGATE_WEIGHTED_MEAN2) {
+            $this->coefstring = 'aggregationcoefextrasum';
         } else if ($this->aggregation == GRADE_AGGREGATE_EXTRACREDIT_MEAN) {
             $this->coefstring = 'aggregationcoefextra';
         } else if ($this->aggregation == GRADE_AGGREGATE_SUM) {