public function addNewLessonInput()
 {
     $newLessonNr = Lesson::getNewLessonNr($this->course->getId());
     $this->addContentAfter('<form method="post">
   <input type="hidden" name="action" value="saveNewLesson" />
   <table class="table">
     <tr>
       <td>' . $newLessonNr . '</td>
       <td><input type="text" name="nameEN" placeholder="Name EN" /></td>
       <td><input type="text" name="nameDE" placeholder="Name DE" /></td>
       <td><input type="text" name="points" placeholder="' . I18n::t('admin.lessonadmin.points') . '" /></td>
       <td><input type="submit" class="btn btn-default" value="' . I18n::t('button.save') . '" /></td>
     </tr>
   </table>
 </form>');
 }