diff --git a/main/gradebook/lib/be/abstractlink.class.php b/main/gradebook/lib/be/abstractlink.class.php
index 9415e76158..078db68ae5 100755
--- a/main/gradebook/lib/be/abstractlink.class.php
+++ b/main/gradebook/lib/be/abstractlink.class.php
@@ -108,7 +108,7 @@ abstract class AbstractLink implements GradebookItem
      */
     public function get_session_id()
     {
-        return $this->session_id;
+        return (int) $this->session_id;
     }
 
     /**
@@ -270,7 +270,7 @@ abstract class AbstractLink implements GradebookItem
      */
     public function getCourseId()
     {
-        return $this->course_id;
+        return (int) $this->course_id;
     }
 
     /**
diff --git a/main/gradebook/lib/be/attendancelink.class.php b/main/gradebook/lib/be/attendancelink.class.php
index 1cec2ca8ac..5f811f2846 100755
--- a/main/gradebook/lib/be/attendancelink.class.php
+++ b/main/gradebook/lib/be/attendancelink.class.php
@@ -49,13 +49,14 @@ class AttendanceLink extends AbstractLink
             return [];
         }
         $tbl_attendance = $this->get_attendance_table();
-        $session_id = api_get_session_id();
+        $sessionId = $this->get_session_id();
+
         $sql = 'SELECT att.id, att.name, att.attendance_qualify_title
                 FROM '.$tbl_attendance.' att
                 WHERE
                     att.c_id = '.$this->course_id.' AND
                     att.active = 1 AND
-                    att.session_id = '.$session_id;
+                    att.session_id = '.$sessionId;
 
         $result = Database::query($sql);
 
@@ -77,10 +78,11 @@ class AttendanceLink extends AbstractLink
     public function has_results()
     {
         $tbl_attendance_result = Database::get_course_table(TABLE_ATTENDANCE_RESULT);
-        $session_id = api_get_session_id();
+        $sessionId = $this->get_session_id();
+
         $sql = 'SELECT count(*) AS number FROM '.$tbl_attendance_result."
                 WHERE
-                    session_id = $session_id AND
+                    session_id = $sessionId AND
                     c_id = '.$this->course_id.' AND
                     attendance_id = '".$this->get_ref_id()."'";
         $result = Database::query($sql);
@@ -97,7 +99,7 @@ class AttendanceLink extends AbstractLink
     public function calc_score($stud_id = null, $type = null)
     {
         $tbl_attendance_result = Database::get_course_table(TABLE_ATTENDANCE_RESULT);
-        $session_id = api_get_session_id();
+        $sessionId = $this->get_session_id();
 
         // get attendance qualify max
         $sql = 'SELECT att.attendance_qualify_max
@@ -105,7 +107,7 @@ class AttendanceLink extends AbstractLink
                 WHERE
                     att.c_id = '.$this->course_id.' AND
                     att.id = '.$this->get_ref_id().' AND
-                    att.session_id='.$session_id;
+                    att.session_id = '.$sessionId;
         $query = Database::query($sql);
         $attendance = Database::fetch_array($query, 'ASSOC');
 
@@ -216,7 +218,6 @@ class AttendanceLink extends AbstractLink
      */
     public function is_valid_link()
     {
-        $session_id = api_get_session_id();
         $sql = 'SELECT count(att.id) FROM '.$this->get_attendance_table().' att
                  WHERE att.c_id = '.$this->course_id.' AND att.id = '.$this->get_ref_id();
         $result = Database::query($sql);
@@ -227,14 +228,14 @@ class AttendanceLink extends AbstractLink
 
     public function get_link()
     {
-        //it was extracts the attendance id
-        $session_id = api_get_session_id();
+        // it was extracts the attendance id
+        $sessionId = $this->get_session_id();
         $sql = 'SELECT * FROM '.$this->get_attendance_table().' att
                 WHERE att.c_id = '.$this->course_id.' AND att.id = '.$this->get_ref_id();
         $result = Database::query($sql);
         $row = Database::fetch_array($result, 'ASSOC');
         $attendance_id = $row['id'];
-        $url = api_get_path(WEB_PATH).'main/attendance/index.php?action=attendance_sheet_list&gradebook=view&attendance_id='.$attendance_id.'&'.api_get_cidreq_params($this->get_course_code(), $session_id);
+        $url = api_get_path(WEB_PATH).'main/attendance/index.php?action=attendance_sheet_list&gradebook=view&attendance_id='.$attendance_id.'&'.api_get_cidreq_params($this->get_course_code(), $sessionId);
 
         return $url;
     }
@@ -263,7 +264,6 @@ class AttendanceLink extends AbstractLink
     private function get_attendance_data()
     {
         $tbl_name = $this->get_attendance_table();
-        $session_id = api_get_session_id();
         if ($tbl_name == '') {
             return false;
         } elseif (!isset($this->attendance_data)) {
diff --git a/main/gradebook/lib/be/evallink.class.php b/main/gradebook/lib/be/evallink.class.php
index 60d4114200..4269ff5e16 100755
--- a/main/gradebook/lib/be/evallink.class.php
+++ b/main/gradebook/lib/be/evallink.class.php
@@ -11,15 +11,7 @@
  */
 abstract class EvalLink extends AbstractLink
 {
-    protected $evaluation = null;
-
-    /**
-     * Constructor.
-     */
-    public function __construct()
-    {
-        parent::__construct();
-    }
+    protected $evaluation;
 
     /**
      * @return bool
@@ -50,12 +42,13 @@ abstract class EvalLink extends AbstractLink
         // course/platform admin can go to the view_results page
         if (api_is_allowed_to_edit()) {
             return 'gradebook_view_result.php?'.api_get_cidreq().'&selecteval='.$eval->get_id();
-        } // students can go to the statistics page (if custom display enabled)
-        elseif (ScoreDisplay::instance()->is_custom()) {
+        } elseif (ScoreDisplay::instance()->is_custom()) {
+            // students can go to the statistics page (if custom display enabled)
+
             return 'gradebook_statistics.php?'.api_get_cidreq().'&selecteval='.$eval->get_id();
-        } else {
-            return null;
         }
+
+        return null;
     }
 
     public function get_name()
diff --git a/main/gradebook/lib/be/exerciselink.class.php b/main/gradebook/lib/be/exerciselink.class.php
index 3a5b323cf7..678537c28a 100755
--- a/main/gradebook/lib/be/exerciselink.class.php
+++ b/main/gradebook/lib/be/exerciselink.class.php
@@ -11,8 +11,8 @@
  */
 class ExerciseLink extends AbstractLink
 {
-    private $course_info = null;
-    private $exercise_table = null;
+    private $course_info;
+    private $exercise_table;
     private $exercise_data = [];
     private $is_hp;
 
@@ -43,11 +43,11 @@ class ExerciseLink extends AbstractLink
         $exerciseTable = $this->get_exercise_table();
         $lpItemTable = Database::get_course_table(TABLE_LP_ITEM);
 
-        $documentPath = api_get_path(SYS_COURSE_PATH).$this->course_code."/document";
+        $documentPath = api_get_path(SYS_COURSE_PATH).$this->course_code.'/document';
         if (empty($this->course_code)) {
             return [];
         }
-        $sessionId = api_get_session_id();
+        $sessionId = $this->get_session_id();
         if (empty($sessionId)) {
             $session_condition = api_get_session_condition(0, true);
         } else {
@@ -149,7 +149,7 @@ class ExerciseLink extends AbstractLink
     public function has_results()
     {
         $tbl_stats = Database::get_main_table(TABLE_STATISTIC_TRACK_E_EXERCISES);
-        $sessionId = api_get_session_id();
+        $sessionId = $this->get_session_id();
         $course_id = api_get_course_int_id($this->get_course_code());
         $sql = "SELECT count(exe_id) AS number 
                 FROM $tbl_stats
@@ -430,14 +430,7 @@ class ExerciseLink extends AbstractLink
      */
     public function get_link()
     {
-        // Status student
-        $user_id = api_get_user_id();
-        $sessionId = api_get_session_id();
-        $course_code = $this->get_course_code();
-        $courseInfo = api_get_course_info($course_code);
-        $courseId = $courseInfo['real_id'];
-        $status_user = api_get_status_of_user_in_course($user_id, $courseId);
-
+        $sessionId = $this->get_session_id();
         $data = $this->get_exercise_data();
         $exerciseId = $data['id'];
         $path = isset($data['path']) ? $data['path'] : '';
diff --git a/main/gradebook/lib/be/forumthreadlink.class.php b/main/gradebook/lib/be/forumthreadlink.class.php
index 4000f8c03e..865a5b8e63 100755
--- a/main/gradebook/lib/be/forumthreadlink.class.php
+++ b/main/gradebook/lib/be/forumthreadlink.class.php
@@ -10,8 +10,8 @@
  */
 class ForumThreadLink extends AbstractLink
 {
-    private $forum_thread_table = null;
-    private $itemprop_table = null;
+    private $forum_thread_table;
+    private $itemprop_table;
 
     /**
      * Constructor.
@@ -38,45 +38,6 @@ class ForumThreadLink extends AbstractLink
         return false;
     }
 
-    /**
-     * Generate an array of exercises that a teacher hasn't created a link for.
-     *
-     * @return array 2-dimensional array - every element contains 2 subelements (id, name)
-     */
-    public function get_not_created_links()
-    {
-        if (empty($this->course_code)) {
-            return [];
-        }
-
-        $tbl_grade_links = Database::get_main_table(TABLE_MAIN_GRADEBOOK_LINK);
-        $sql = 'SELECT thread_id,thread_title,thread_title_qualify 
-                FROM '.$this->get_forum_thread_table().'
-                forum_thread WHERE thread_id NOT IN
-                (
-                    SELECT ref_id FROM '.$tbl_grade_links.' 
-                    WHERE 
-                        type = '.LINK_FORUM_THREAD.' AND
-                        c_id = '.intval($this->course_id).'
-                ) 
-                AND forum_thread.session_id='.api_get_session_id();
-
-        $result = Database::query($sql);
-        $cats = [];
-        while ($data = Database::fetch_array($result)) {
-            if (isset($data['thread_title_qualify']) && $data['thread_title_qualify'] != "") {
-                $cats[] = [
-                    $data['thread_id'],
-                    $data['thread_title_qualify'],
-                ];
-            } else {
-                $cats[] = [$data['thread_id'], $data['thread_title']];
-            }
-        }
-
-        return $cats;
-    }
-
     /**
      * Generate an array of all exercises available.
      *
@@ -90,10 +51,10 @@ class ForumThreadLink extends AbstractLink
 
         $tbl_grade_links = Database::get_course_table(TABLE_FORUM_THREAD);
         $tbl_item_property = Database::get_course_table(TABLE_ITEM_PROPERTY);
-        $session_id = api_get_session_id();
+        $sessionId = $this->get_session_id();
 
-        if ($session_id) {
-            $session_condition = 'tl.session_id='.api_get_session_id();
+        if ($sessionId) {
+            $session_condition = 'tl.session_id='.$sessionId;
         } else {
             $session_condition = '(tl.session_id = 0 OR tl.session_id IS NULL)';
         }
@@ -286,9 +247,9 @@ class ForumThreadLink extends AbstractLink
         $thread_title_qualify = isset($this->exercise_data['thread_title_qualify']) ? $this->exercise_data['thread_title_qualify'] : '';
         if (isset($thread_title_qualify) && $thread_title_qualify != '') {
             return $this->exercise_data['thread_title_qualify'];
-        } else {
-            return $thread_title;
         }
+
+        return $thread_title;
     }
 
     /**
@@ -304,11 +265,12 @@ class ForumThreadLink extends AbstractLink
      */
     public function is_valid_link()
     {
+        $sessionId = $this->get_session_id();
         $sql = 'SELECT count(id) from '.$this->get_forum_thread_table().'
                 WHERE 
                     c_id = '.$this->course_id.' AND 
                     thread_id = '.$this->get_ref_id().' AND 
-                    session_id='.api_get_session_id();
+                    session_id='.$sessionId;
         $result = Database::query($sql);
         $number = Database::fetch_row($result);
 
@@ -317,7 +279,7 @@ class ForumThreadLink extends AbstractLink
 
     public function get_link()
     {
-        $sessionId = api_get_session_id();
+        $sessionId = $this->get_session_id();
         //it was extracts the forum id
         $sql = 'SELECT * FROM '.$this->get_forum_thread_table()."
                 WHERE
@@ -355,7 +317,7 @@ class ForumThreadLink extends AbstractLink
     {
         $ref_id = $this->get_ref_id();
         if (!empty($ref_id)) {
-            //Cleans forum
+            // Cleans forum
             $sql = 'UPDATE '.$this->get_forum_thread_table().' SET
                     thread_qualify_max = 0,
                     thread_weight = 0,
@@ -375,9 +337,9 @@ class ForumThreadLink extends AbstractLink
 
     private function get_exercise_data()
     {
-        $session_id = api_get_session_id();
-        if ($session_id) {
-            $session_condition = 'session_id='.api_get_session_id();
+        $sessionId = $this->get_session_id();
+        if ($sessionId) {
+            $session_condition = 'session_id = '.$sessionId;
         } else {
             $session_condition = '(session_id = 0 OR session_id IS NULL)';
         }
diff --git a/main/gradebook/lib/be/learnpathlink.class.php b/main/gradebook/lib/be/learnpathlink.class.php
index 725b429ef8..0311b3831a 100755
--- a/main/gradebook/lib/be/learnpathlink.class.php
+++ b/main/gradebook/lib/be/learnpathlink.class.php
@@ -11,9 +11,9 @@
  */
 class LearnpathLink extends AbstractLink
 {
-    private $course_info = null;
-    private $learnpath_table = null;
-    private $learnpath_data = null;
+    private $course_info;
+    private $learnpath_table;
+    private $learnpath_data;
 
     /**
      * Constructor.
@@ -35,7 +35,7 @@ class LearnpathLink extends AbstractLink
             return [];
         }
 
-        $session_id = api_get_session_id();
+        $session_id = $this->get_session_id();
         if (empty($session_id)) {
             $session_condition = api_get_session_condition(0, true);
         } else {
@@ -154,7 +154,7 @@ class LearnpathLink extends AbstractLink
      */
     public function get_link()
     {
-        $session_id = api_get_session_id();
+        $session_id = $this->get_session_id();
         $url = api_get_path(WEB_CODE_PATH).'lp/lp_controller.php?'.api_get_cidreq_params(
             $this->get_course_code(),
                 $session_id
diff --git a/main/gradebook/lib/be/studentpublicationlink.class.php b/main/gradebook/lib/be/studentpublicationlink.class.php
index 9d7b671d07..1ff9318d67 100755
--- a/main/gradebook/lib/be/studentpublicationlink.class.php
+++ b/main/gradebook/lib/be/studentpublicationlink.class.php
@@ -82,7 +82,8 @@ class StudentPublicationLink extends AbstractLink
             return [];
         }
         $em = Database::getManager();
-        $session = $em->find('ChamiloCoreBundle:Session', api_get_session_id());
+        $sessionId = $this->get_session_id();
+        $session = $em->find('ChamiloCoreBundle:Session', $sessionId);
         /*
         if (empty($session_id)) {
             $session_condition = api_get_session_condition(0, true);
@@ -128,7 +129,7 @@ class StudentPublicationLink extends AbstractLink
         $id = $data['id'];
 
         $em = Database::getManager();
-        $session = $em->find('ChamiloCoreBundle:Session', api_get_session_id());
+        $session = $em->find('ChamiloCoreBundle:Session', $this->get_session_id());
         $results = $em
             ->getRepository('ChamiloCourseBundle:CStudentPublication')
             ->findBy([
@@ -155,7 +156,7 @@ class StudentPublicationLink extends AbstractLink
             return [];
         }
         $id = $data['id'];
-        $session = $em->find('ChamiloCoreBundle:Session', api_get_session_id());
+        $session = $em->find('ChamiloCoreBundle:Session', $this->get_session_id());
 
         $assignment = $em
             ->getRepository('ChamiloCourseBundle:CStudentPublication')
@@ -302,8 +303,8 @@ class StudentPublicationLink extends AbstractLink
 
     public function get_link()
     {
-        $session_id = api_get_session_id();
-        $url = api_get_path(WEB_PATH).'main/work/work.php?'.api_get_cidreq_params($this->get_course_code(), $session_id).'&id='.$this->exercise_data['id'].'&gradebook=view';
+        $sessionId = $this->get_session_id();
+        $url = api_get_path(WEB_PATH).'main/work/work.php?'.api_get_cidreq_params($this->get_course_code(), $sessionId).'&id='.$this->exercise_data['id'].'&gradebook=view';
 
         return $url;
     }
@@ -329,7 +330,7 @@ class StudentPublicationLink extends AbstractLink
         $sql = 'SELECT count(id) FROM '.$this->get_studpub_table().'
                 WHERE 
                     c_id = "'.$this->course_id.'" AND 
-                    id = '.$id.'';
+                    id = '.$id;
         $result = Database::query($sql);
         $number = Database::fetch_row($result);
 
diff --git a/main/gradebook/lib/be/surveylink.class.php b/main/gradebook/lib/be/surveylink.class.php
index 5287bc1ba3..d4b4728272 100755
--- a/main/gradebook/lib/be/surveylink.class.php
+++ b/main/gradebook/lib/be/surveylink.class.php
@@ -10,7 +10,7 @@
  */
 class SurveyLink extends AbstractLink
 {
-    private $survey_table = null;
+    private $survey_table;
     private $survey_data = [];
 
     /**
@@ -32,6 +32,9 @@ class SurveyLink extends AbstractLink
         return $this->survey_data['code'].': '.self::html_to_text($this->survey_data['title']);
     }
 
+    /**
+     * @return string
+     */
     public function get_description()
     {
         $this->get_survey_data();
@@ -39,6 +42,9 @@ class SurveyLink extends AbstractLink
         return $this->survey_data['subtitle'];
     }
 
+    /**
+     * @return string
+     */
     public function get_type_name()
     {
         return get_lang('Survey');
@@ -75,10 +81,11 @@ class SurveyLink extends AbstractLink
             die('Error in get_all_links() : course code not set');
         }
         $tbl_survey = $this->get_survey_table();
-        $session_id = api_get_session_id();
-        $course_id = api_get_course_int_id();
+        $sessionId = $this->get_session_id();
+        $course_id = $this->getCourseId();
+
         $sql = 'SELECT survey_id, title, code FROM '.$tbl_survey.'
-                WHERE c_id = '.$course_id.' AND session_id = '.intval($session_id);
+                WHERE c_id = '.$course_id.' AND session_id = '.$sessionId;
         $result = Database::query($sql);
         while ($data = Database::fetch_array($result)) {
             $links[] = [
@@ -99,8 +106,10 @@ class SurveyLink extends AbstractLink
      */
     public function has_results()
     {
-        $ref_id = intval($this->get_ref_id());
-        $session_id = api_get_session_id();
+        $ref_id = $this->get_ref_id();
+        $sessionId = $this->get_session_id();
+        $courseId = $this->getCourseId();
+
         $tbl_survey = Database::get_course_table(TABLE_SURVEY);
         $tbl_survey_invitation = Database::get_course_table(TABLE_SURVEY_INVITATION);
         $sql = "SELECT
@@ -108,10 +117,10 @@ class SurveyLink extends AbstractLink
                 FROM $tbl_survey AS s
                 JOIN $tbl_survey_invitation AS i ON s.code = i.survey_code
                 WHERE
-                    s.c_id = {$this->course_id} AND
-                    i.c_id = {$this->course_id} AND
+                    s.c_id = $courseId AND
+                    i.c_id = $courseId AND
                     s.survey_id = $ref_id AND
-                    i.session_id = $session_id";
+                    i.session_id = $sessionId";
 
         $sql_result = Database::query($sql);
         $data = Database::fetch_array($sql_result);
@@ -132,12 +141,11 @@ class SurveyLink extends AbstractLink
         // Note: Max score is assumed to be always 1 for surveys,
         // only student's participation is to be taken into account.
         $max_score = 1;
-
-        $ref_id = intval($this->get_ref_id());
-        $session_id = api_get_session_id();
+        $ref_id = $this->get_ref_id();
+        $sessionId = $this->get_session_id();
+        $courseId = $this->getCourseId();
         $tbl_survey = Database::get_course_table(TABLE_SURVEY);
         $tbl_survey_invitation = Database::get_course_table(TABLE_SURVEY_INVITATION);
-
         $get_individual_score = !is_null($stud_id);
 
         $sql = "SELECT i.answered
@@ -145,10 +153,10 @@ class SurveyLink extends AbstractLink
                 JOIN $tbl_survey_invitation AS i
                 ON s.code = i.survey_code
                 WHERE
-                    s.c_id = {$this->course_id} AND
-                    i.c_id = {$this->course_id} AND
+                    s.c_id = $courseId AND
+                    i.c_id = $courseId AND
                     s.survey_id = $ref_id AND
-                    i.session_id = $session_id
+                    i.session_id = $sessionId
                 ";
 
         if ($get_individual_score) {
@@ -204,12 +212,14 @@ class SurveyLink extends AbstractLink
      */
     public function is_valid_link()
     {
-        $session_id = api_get_session_id();
+        $sessionId = $this->get_session_id();
+        $courseId = $this->getCourseId();
+
         $sql = 'SELECT count(survey_id) FROM '.$this->get_survey_table().'
                  WHERE
-                    c_id = '.$this->course_id.' AND
-                    survey_id = '.intval($this->get_ref_id()).' AND
-                    session_id = '.intval($session_id);
+                    c_id = '.$courseId.' AND
+                    survey_id = '.$this->get_ref_id().' AND
+                    session_id = '.$sessionId;
         $result = Database::query($sql);
         $number = Database::fetch_row($result);
 
@@ -222,20 +232,24 @@ class SurveyLink extends AbstractLink
             return null;
         }
 
-        if (api_is_allowed_to_edit()) { // Let students make access only through "Surveys" tool.
+        if (api_is_allowed_to_edit()) {
+            // Let students make access only through "Surveys" tool.
             $tbl_name = $this->get_survey_table();
-            $session_id = api_get_session_id();
+            $sessionId = $this->get_session_id();
+            $courseId = $this->getCourseId();
+
             if ($tbl_name != '') {
-                $sql = 'SELECT survey_id FROM '.$this->get_survey_table().'
+                $sql = 'SELECT survey_id 
+                        FROM '.$this->get_survey_table().'
                         WHERE
-                            c_id = '.$this->course_id.' AND
-                            survey_id = '.intval($this->get_ref_id()).' AND
-                            session_id = '.intval($session_id).' ';
+                            c_id = '.$courseId.' AND
+                            survey_id = '.$this->get_ref_id().' AND
+                            session_id = '.$sessionId;
                 $result = Database::query($sql);
                 $row = Database::fetch_array($result, 'ASSOC');
                 $survey_id = $row['survey_id'];
 
-                return api_get_path(WEB_PATH).'main/survey/reporting.php?'.api_get_cidreq_params($this->get_course_code(), $session_id).'&survey_id='.$survey_id;
+                return api_get_path(WEB_PATH).'main/survey/reporting.php?'.api_get_cidreq_params($this->get_course_code(), $sessionId).'&survey_id='.$survey_id;
             }
         }
 
@@ -270,16 +284,18 @@ class SurveyLink extends AbstractLink
     private function get_survey_data()
     {
         $tbl_name = $this->get_survey_table();
-        $session_id = api_get_session_id();
 
         if ($tbl_name == '') {
             return false;
         } elseif (empty($this->survey_data)) {
+            $courseId = $this->getCourseId();
+            $sessionId = $this->get_session_id();
+
             $sql = 'SELECT * FROM '.$tbl_name.'
                     WHERE
-                        c_id = '.$this->course_id.' AND
-                        survey_id = '.intval($this->get_ref_id()).' AND
-                        session_id = '.intval($session_id);
+                        c_id = '.$courseId.' AND
+                        survey_id = '.$this->get_ref_id().' AND
+                        session_id = '.$sessionId;
             $query = Database::query($sql);
             $this->survey_data = Database::fetch_array($query);
         }
@@ -287,6 +303,11 @@ class SurveyLink extends AbstractLink
         return $this->survey_data;
     }
 
+    /**
+     * @param string $string
+     *
+     * @return string
+     */
     private static function html_to_text($string)
     {
         return strip_tags($string);
diff --git a/main/mySpace/myStudents.php b/main/mySpace/myStudents.php
index 38c8f9cc42..7eb1529e16 100755
--- a/main/mySpace/myStudents.php
+++ b/main/mySpace/myStudents.php
@@ -1700,10 +1700,9 @@ if (empty($details)) {
                 }
                 $lp_name = !empty($lp_name) ? $lp_name : get_lang('NoLearnpath');
 
+                $css_class = 'row_even';
                 if ($i % 2) {
                     $css_class = 'row_odd';
-                } else {
-                    $css_class = 'row_even';
                 }
 
                 echo '<tr class="'.$css_class.'"><td>'.$exercices['title'].'</td>';