diff --git a/mod/quiz/locallib.php b/mod/quiz/locallib.php
index 0e96212c95d..83f19c24257 100644
--- a/mod/quiz/locallib.php
+++ b/mod/quiz/locallib.php
@@ -581,25 +581,21 @@ function quiz_save_best_grade($quiz, $userid = null, $attempts = array()) {
 /**
  * Calculate the overall grade for a quiz given a number of attempts by a particular user.
  *
- * @return float          The overall grade
- * @param object $quiz    The quiz for which the best grade is to be calculated
- * @param array $attempts An array of all the attempts of the user at the quiz
+ * @param object $quiz    the quiz settings object.
+ * @param array $attempts an array of all the user's attempts at this quiz in order.
+ * @return float          the overall grade
  */
 function quiz_calculate_best_grade($quiz, $attempts) {
 
     switch ($quiz->grademethod) {
 
         case QUIZ_ATTEMPTFIRST:
-            foreach ($attempts as $attempt) {
-                return $attempt->sumgrades;
-            }
-            break;
+            $firstattempt = reset($attempts);
+            return $firstattempt->sumgrades;
 
         case QUIZ_ATTEMPTLAST:
-            foreach ($attempts as $attempt) {
-                $final = $attempt->sumgrades;
-            }
-            return $final;
+            $lastattempt = end($attempts);
+            return $lastattempt->sumgrades;
 
         case QUIZ_GRADEAVERAGE:
             $sum = 0;
@@ -608,10 +604,10 @@ function quiz_calculate_best_grade($quiz, $attempts) {
                 $sum += $attempt->sumgrades;
                 $count++;
             }
-            return (float)$sum/$count;
+            return (float) $sum/$count;
 
-        default:
         case QUIZ_GRADEHIGHEST:
+        default:
             $max = 0;
             foreach ($attempts as $attempt) {
                 if ($attempt->sumgrades > $max) {
diff --git a/mod/quiz/report/overview/report.php b/mod/quiz/report/overview/report.php
index bf5ab291674..5ba30b8015b 100644
--- a/mod/quiz/report/overview/report.php
+++ b/mod/quiz/report/overview/report.php
@@ -596,7 +596,7 @@ class quiz_overview_report extends quiz_default_report {
             } else {
                 $params = array();
             }
-            $attemptsql .= "{quiz_attempts}.quiz =? AND preview = 0";
+            $attemptsql .= "{quiz_attempts}.quiz = ? AND preview = 0";
             $params[] = $quiz->id;
         } else {
             list($asql, $params) = $DB->get_in_or_equal($attemptids);
@@ -613,10 +613,10 @@ class quiz_overview_report extends quiz_default_report {
             //not just those that have changed.
             $sql = "SELECT qa2.* FROM {quiz_attempts} qa2 WHERE " .
                     "qa2.userid IN (SELECT DISTINCT userid FROM {quiz_attempts} WHERE $attemptsql) " .
-                    "AND qa2.timefinish > 0 AND qa2.quiz = ?";
+                    "AND qa2.timefinish > 0 AND qa2.quiz = ? ORDER BY qa2.userid, qa2.attempt";
             $params[] = $quiz->id;
         } else {
-            $sql = "SELECT * FROM {quiz_attempts} WHERE $attemptsql AND timefinish > 0";
+            $sql = "SELECT * FROM {quiz_attempts} WHERE $attemptsql AND timefinish > 0 ORDER BY userid, attempt";
         }
         if ($attempts = $DB->get_records_sql($sql, $params)) {
             $attemptsbyuser = quiz_report_index_by_keys($attempts, array('userid', 'id'));