diff --git a/add_form.php b/add_form.php
index 849b86d..3ce9fa5 100644
--- a/add_form.php
+++ b/add_form.php
@@ -47,8 +47,8 @@ class mod_attforblock_add_form extends moodleform {
                 break;
             case VISIBLEGROUPS:
                 $radio=array();
-                $radio[] = &MoodleQuickForm::createElement('radio', 'sessiontype', '', get_string('commonsession','attforblock'), attforblock::SESSION_COMMON);
-                $radio[] = &MoodleQuickForm::createElement('radio', 'sessiontype', '', get_string('groupsession','attforblock'), attforblock::SESSION_GROUP);
+                $radio[] = &$mform->createElement('radio', 'sessiontype', '', get_string('commonsession','attforblock'), attforblock::SESSION_COMMON);
+                $radio[] = &$mform->createElement('radio', 'sessiontype', '', get_string('groupsession','attforblock'), attforblock::SESSION_GROUP);
                 $mform->addGroup($radio, 'sessiontype', get_string('sessiontype','attforblock'), ' ', false);
                 $mform->addHelpButton('sessiontype', 'sessiontype', 'attforblock');
                 $mform->setDefault('sessiontype', attforblock::SESSION_COMMON);
@@ -90,8 +90,8 @@ class mod_attforblock_add_form extends moodleform {
             $minutes[$i] = sprintf("%02d",$i);
         }
         $durtime = array();
-        $durtime[] =& MoodleQuickForm::createElement('select', 'hours', get_string('hour', 'form'), $hours, false, true);
-		$durtime[] =& MoodleQuickForm::createElement('select', 'minutes', get_string('minute', 'form'), $minutes, false, true);
+        $durtime[] =& $mform->createElement('select', 'hours', get_string('hour', 'form'), $hours, false, true);
+		$durtime[] =& $mform->createElement('select', 'minutes', get_string('minute', 'form'), $minutes, false, true);
         $mform->addGroup($durtime, 'durtime', get_string('duration','attforblock'), array(' '), true);
         
         $mform->addElement('date_selector', 'sessionenddate', get_string('sessionenddate','attforblock'));
@@ -99,24 +99,24 @@ class mod_attforblock_add_form extends moodleform {
         
         $sdays = array();
 		if ($CFG->calendar_startwday === '0') { //week start from sunday
-        	$sdays[] =& MoodleQuickForm::createElement('checkbox', 'Sun', '', get_string('sunday','calendar'));
+        	$sdays[] =& $mform->createElement('checkbox', 'Sun', '', get_string('sunday','calendar'));
 		}
-        $sdays[] =& MoodleQuickForm::createElement('checkbox', 'Mon', '', get_string('monday','calendar'));
-        $sdays[] =& MoodleQuickForm::createElement('checkbox', 'Tue', '', get_string('tuesday','calendar'));
-        $sdays[] =& MoodleQuickForm::createElement('checkbox', 'Wed', '', get_string('wednesday','calendar'));
-        $sdays[] =& MoodleQuickForm::createElement('checkbox', 'Thu', '', get_string('thursday','calendar'));
-        $sdays[] =& MoodleQuickForm::createElement('checkbox', 'Fri', '', get_string('friday','calendar'));
-        $sdays[] =& MoodleQuickForm::createElement('checkbox', 'Sat', '', get_string('saturday','calendar'));
+        $sdays[] =& $mform->createElement('checkbox', 'Mon', '', get_string('monday','calendar'));
+        $sdays[] =& $mform->createElement('checkbox', 'Tue', '', get_string('tuesday','calendar'));
+        $sdays[] =& $mform->createElement('checkbox', 'Wed', '', get_string('wednesday','calendar'));
+        $sdays[] =& $mform->createElement('checkbox', 'Thu', '', get_string('thursday','calendar'));
+        $sdays[] =& $mform->createElement('checkbox', 'Fri', '', get_string('friday','calendar'));
+        $sdays[] =& $mform->createElement('checkbox', 'Sat', '', get_string('saturday','calendar'));
 		if ($CFG->calendar_startwday !== '0') { //week start from sunday
-        	$sdays[] =& MoodleQuickForm::createElement('checkbox', 'Sun', '', get_string('sunday','calendar'));
+        	$sdays[] =& $mform->createElement('checkbox', 'Sun', '', get_string('sunday','calendar'));
 		}
         $mform->addGroup($sdays, 'sdays', get_string('sessiondays','attforblock'), array(' '), true);
 		$mform->disabledIf('sdays', 'addmultiply', 'notchecked');
         
         $period = array(1=>1,2,3,4,5,6,7,8);
         $periodgroup = array();
-        $periodgroup[] =& MoodleQuickForm::createElement('select', 'period', '', $period, false, true);
-        $periodgroup[] =& MoodleQuickForm::createElement('static', 'perioddesc', '', get_string('week','attforblock'));
+        $periodgroup[] =& $mform->createElement('select', 'period', '', $period, false, true);
+        $periodgroup[] =& $mform->createElement('static', 'perioddesc', '', get_string('week','attforblock'));
         $mform->addGroup($periodgroup, 'periodgroup', get_string('period','attforblock'), array(' '), false);
 		$mform->disabledIf('periodgroup', 'addmultiply', 'notchecked');
         
diff --git a/duration_form.php b/duration_form.php
index 6b4c810..0403b93 100644
--- a/duration_form.php
+++ b/duration_form.php
@@ -37,8 +37,8 @@ class mod_attforblock_duration_form extends moodleform {
         for ($i=0; $i<60; $i+=5) {
             $minutes[$i] = sprintf("%02d",$i);
         }
-        $durselect[] =& MoodleQuickForm::createElement('select', 'hours', '', $hours);
-		$durselect[] =& MoodleQuickForm::createElement('select', 'minutes', '', $minutes, false, true);
+        $durselect[] =& $mform->createElement('select', 'hours', '', $hours);
+		$durselect[] =& $mform->createElement('select', 'minutes', '', $minutes, false, true);
 		$mform->addGroup($durselect, 'durtime', get_string('newduration','attforblock'), array(' '), true);
 		
         $mform->addElement('hidden', 'ids', $ids);
diff --git a/export_form.php b/export_form.php
index 1d61008..0a91d81 100644
--- a/export_form.php
+++ b/export_form.php
@@ -43,8 +43,8 @@ class mod_attforblock_export_form extends moodleform {
         $mform->addElement('select', 'group', get_string('group'), $grouplist);
         
         $ident = array();
-        $ident[] =& MoodleQuickForm::createElement('checkbox', 'id', '', get_string('studentid', 'attforblock'));
-        $ident[] =& MoodleQuickForm::createElement('checkbox', 'uname', '', get_string('username'));
+        $ident[] =& $mform->createElement('checkbox', 'id', '', get_string('studentid', 'attforblock'));
+        $ident[] =& $mform->createElement('checkbox', 'uname', '', get_string('username'));
         $mform->addGroup($ident, 'ident', get_string('identifyby','attforblock'), array('<br />'), true);
         $mform->setDefaults(array('ident[id]' => true, 'ident[uname]' => true));
         
diff --git a/locallib.php b/locallib.php
index 7782128..26a68ff 100644
--- a/locallib.php
+++ b/locallib.php
@@ -231,7 +231,7 @@ class att_page_with_filter_controls {
     }
 
     private function calc_sessgroupslist_sesstype() {
-        global $USER, $SESSION;
+        global $SESSION;
         
         if (!array_key_exists('attsessiontype', $SESSION)) {
             $SESSION->attsessiontype = array($this->cm->course => self::SESSTYPE_ALL);
@@ -277,7 +277,7 @@ class att_page_with_filter_controls {
     }
     
     private function calc_sessgroupslist() {
-        global $PAGE;
+        global $USER, $PAGE;
         
         $this->sessgroupslist = array();
         $groupmode = groups_get_activity_groupmode($this->cm);
@@ -533,7 +533,7 @@ class attforblock {
         $this->cm           = $cm;
         $this->course       = $course;
         if (is_null($context)) {
-            $this->context = get_context_instance(CONTEXT_MODULE, $this->cm->id);
+            $this->context = context_module::instance_by_id($this->cm->id);
         } else {
             $this->context = $context;
         }
@@ -803,7 +803,7 @@ class attforblock {
             }
         }
 
-        $rec = new object();
+        $rec = new stdClass();
         $rec->id = $this->pageparams->sessionid;
         $rec->lasttaken = $now;
         $rec->lasttakenby = $USER->id;
@@ -886,8 +886,6 @@ class attforblock {
     }
 
     public function get_statuses($onlyvisible = true) {
-        global $DB;
-
         if (!isset($this->statuses)) {
             $this->statuses = att_get_statuses($this->id, $onlyvisible);
         }
@@ -937,8 +935,6 @@ class attforblock {
     }
 
     public function get_user_stat($userid) {
-        global $DB;
-
         $ret = array();
         $ret['completed'] = $this->get_user_taken_sessions_count($userid);
         $ret['statuses'] = $this->get_user_statuses_stat($userid);
@@ -947,8 +943,6 @@ class attforblock {
     }
 
     public function get_user_taken_sessions_count($userid) {
-        global $DB;
-
         if (!array_key_exists($userid, $this->usertakensesscount))
             $this->usertakensesscount[$userid] = att_get_user_taken_sessions_count($this->id, $this->course->startdate, $userid);
 
diff --git a/renderables.php b/renderables.php
index 99e9b9d..16fe825 100644
--- a/renderables.php
+++ b/renderables.php
@@ -210,8 +210,6 @@ class attforblock_manage_data implements renderable {
      * @param attforblock $att instance
      */
     public function __construct(attforblock $att) {
-        global $DB;
-
         $this->perm = $att->perm;
 
         $this->sessions = $att->get_filtered_sessions();
diff --git a/sessions.php b/sessions.php
index 679dabb..f2067fa 100644
--- a/sessions.php
+++ b/sessions.php
@@ -207,7 +207,8 @@ function construct_sessions_data_for_add($formdata) {
         while ($sdate < $enddate) {
             if($sdate < $startweek + WEEKSECS) {
                 $dinfo = usergetdate($sdate);
-                if(key_exists($wdaydesc[$dinfo['wday']], $formdata->sdays)) {
+                if(array_key_exists($wdaydesc[$dinfo['wday']], $formdata->sdays)) {
+                    $sess = new stdClass();
                     $sess->sessdate =  usergetmidnight($sdate) + $starttime;
                     $sess->duration = $duration;
                     $sess->descriptionitemid = $formdata->sdescription['itemid'];
@@ -224,6 +225,7 @@ function construct_sessions_data_for_add($formdata) {
             }
         }
     } else {
+        $sess = new stdClass();
         $sess->sessdate = $formdata->sessiondate;
         $sess->duration = $duration;
         $sess->descriptionitemid = $formdata->sdescription['itemid'];
diff --git a/update_form.php b/update_form.php
index 1ca26d4..4425c41 100644
--- a/update_form.php
+++ b/update_form.php
@@ -50,8 +50,8 @@ class mod_attforblock_update_form extends moodleform {
         for ($i=0; $i<60; $i+=5) {
             $minutes[$i] = sprintf("%02d",$i);
         }
-        $durselect[] =& MoodleQuickForm::createElement('select', 'hours', '', $hours);
-		$durselect[] =& MoodleQuickForm::createElement('select', 'minutes', '', $minutes, false, true);
+        $durselect[] =& $mform->createElement('select', 'hours', '', $hours);
+		$durselect[] =& $mform->createElement('select', 'minutes', '', $minutes, false, true);
 		$mform->addGroup($durselect, 'durtime', get_string('duration','attforblock'), array(' '), true);
 		
         $mform->addElement('editor', 'sdescription', get_string('description', 'attforblock'), null, $defopts);