diff --git a/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterialAssignmentTableGUI.php b/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterialAssignmentTableGUI.php
index 50bd54d9b64f..dac711fcd14a 100644
--- a/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterialAssignmentTableGUI.php
+++ b/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterialAssignmentTableGUI.php
@@ -1,6 +1,5 @@
 <?php
 
-declare(strict_types=0);
 /**
  * This file is part of ILIAS, a powerful learning management system
  * published by ILIAS open source e-Learning e.V.
@@ -17,6 +16,8 @@
  *
  *********************************************************************/
 
+declare(strict_types=0);
+
 /**
  * TableGUI for material assignments of course objectives
  * @author  Stefan Meyer <smeyer.ilias@gmx.de>
@@ -36,6 +37,7 @@ public function __construct(object $a_parent_obj, ilObject $a_course_obj, int $a
         $this->objectDefinition = $DIC['objDefinition'];
         $this->objective_id = $a_objective_id;
 
+        $this->setId('tbl_crs_obj_mat_assignment');
         parent::__construct($a_parent_obj, 'materialAssignment');
         $this->lng->loadLanguageModule('crs');
 
@@ -46,7 +48,7 @@ public function __construct(object $a_parent_obj, ilObject $a_course_obj, int $a
         $this->setFormAction($this->ctrl->getFormAction($a_parent_obj));
         $this->setRowTemplate("tpl.crs_objective_list_materials_row.html", "Modules/Course");
         $this->setDefaultOrderField('title');
-        $this->setLimit(200);
+        $this->setShowRowsSelector(true);
         $this->setNoEntriesText($this->lng->txt('crs_no_objective_lms_found'));
         $this->addCommandButton('updateMaterialAssignment', $this->lng->txt('crs_wiz_next'));
         $this->initObjectiveAssignments();
diff --git a/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterials.php b/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterials.php
index fbea60a3480f..b4ceb26ac6cd 100644
--- a/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterials.php
+++ b/Modules/Course/classes/Objectives/class.ilCourseObjectiveMaterials.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=0);
-
 /**
  * This file is part of ILIAS, a powerful learning management system
  * published by ILIAS open source e-Learning e.V.
@@ -18,6 +16,8 @@
  *
  *********************************************************************/
 
+declare(strict_types=0);
+
 /**
  * class ilCourseObjectiveMaterials
  * @author Stefan Meyer <meyer@leifos.com>
@@ -293,6 +293,26 @@ public function add(): int
         return $next_id;
     }
 
+    public function deleteMaterial(int $ref_id, int $obj_id): bool
+    {
+        $query = "DELETE FROM crs_objective_lm " .
+            "WHERE objective_id = " . $this->db->quote($this->getObjectiveId(), 'integer') . " " .
+            "AND ref_id = " . $this->db->quote($ref_id, 'integer') . " " .
+            "AND obj_id = " . $this->db->quote($obj_id, 'integer');
+        $this->db->manipulate($query);
+        return true;
+    }
+
+    public function isMaterialAssigned(int $ref_id, int $obj_id): bool
+    {
+        $query = "SELECT * FROM crs_objective_lm " .
+            "WHERE ref_id = " . $this->db->quote($ref_id, 'integer') . " " .
+            "AND obj_id = " . $this->db->quote($obj_id, 'integer') . " " .
+            "AND objective_id = " . $this->db->quote($this->getObjectiveId(), 'integer') . " ";
+        $res = $this->db->query($query);
+        return (bool) $res->numRows();
+    }
+
     public function delete(int $lm_id): bool
     {
         if (!$lm_id) {
diff --git a/Modules/Course/classes/Objectives/class.ilCourseObjectivesGUI.php b/Modules/Course/classes/Objectives/class.ilCourseObjectivesGUI.php
index ee1573530b03..53afb77b5599 100644
--- a/Modules/Course/classes/Objectives/class.ilCourseObjectivesGUI.php
+++ b/Modules/Course/classes/Objectives/class.ilCourseObjectivesGUI.php
@@ -1,7 +1,5 @@
 <?php
 
-declare(strict_types=0);
-
 /**
  * This file is part of ILIAS, a powerful learning management system
  * published by ILIAS open source e-Learning e.V.
@@ -18,6 +16,8 @@
  *
  *********************************************************************/
 
+declare(strict_types=0);
+
 use ILIAS\UI\Component\Listing\Workflow\Step;
 use ILIAS\UI\Component\Listing\Workflow\Factory as Workflow;
 use ILIAS\UI\Renderer as UIRenderer;
@@ -399,6 +399,38 @@ protected function materialAssignment(): void
         $this->tpl->setContent($table->getHTML());
     }
 
+    /**
+     * @return int[]
+     */
+    private function getIntArrayFromPost(string $key): array
+    {
+        if ($this->http->wrapper()->post()->has($key)) {
+            return $this->http->wrapper()->post()->retrieve(
+                $key,
+                $this->refinery->kindlyTo()->listOf(
+                    $this->refinery->kindlyTo()->int()
+                )
+            );
+        }
+        return [];
+    }
+
+    /**
+     * @return string[]
+     */
+    private function getStringArrayFromPost(string $key): array
+    {
+        if ($this->http->wrapper()->post()->has($key)) {
+            return $this->http->wrapper()->post()->retrieve(
+                $key,
+                $this->refinery->kindlyTo()->listOf(
+                    $this->refinery->kindlyTo()->string()
+                )
+            );
+        }
+        return [];
+    }
+
     protected function updateMaterialAssignment(): void
     {
         if (!$this->access->checkAccess('write', '', $this->course_obj->getRefId())) {
@@ -410,38 +442,36 @@ protected function updateMaterialAssignment(): void
         }
 
         $this->__initLMObject($this->initObjectiveIdFromQuery());
-        $this->objectives_lm_obj->deleteAll();
 
-        $materials = [];
-        if ($this->http->wrapper()->post()->has('materials')) {
-            $materials = $this->http->wrapper()->post()->retrieve(
-                'materials',
-                $this->refinery->kindlyTo()->listOf(
-                    $this->refinery->kindlyTo()->int()
-                )
-            );
-        }
-        foreach ($materials as $node_id) {
-            $obj_id = $this->objectDataCache->lookupObjId((int) $node_id);
-            $type = $this->objectDataCache->lookupType($obj_id);
+        $visibleMaterials = $this->getIntArrayFromPost('visible_materials');
+        $visibleChapters = $this->getStringArrayFromPost('visible_chapters');
+        $materials = $this->getIntArrayFromPost('materials');
+        $chapters = $this->getStringArrayFromPost('chapters');
 
+        foreach ($visibleMaterials as $node_id) {
+            $obj_id = $this->objectDataCache->lookupObjId((int) $node_id);
+            if (!in_array($node_id, $materials)) {
+                $this->objectives_lm_obj->deleteMaterial($node_id, $obj_id);
+                continue;
+            }
+            if ($this->objectives_lm_obj->isMaterialAssigned($node_id, $obj_id)) {
+                continue;
+            }
             $this->objectives_lm_obj->setLMRefId($node_id);
             $this->objectives_lm_obj->setLMObjId($obj_id);
-            $this->objectives_lm_obj->setType($type);
+            $this->objectives_lm_obj->setType($this->objectDataCache->lookupType($obj_id));
             $this->objectives_lm_obj->add();
         }
-        $chapters = [];
-        if ($this->http->wrapper()->post()->has('chapters')) {
-            $chapters = $this->http->wrapper()->post()->retrieve(
-                'chapters',
-                $this->refinery->kindlyTo()->listOf(
-                    $this->refinery->kindlyTo()->string()
-                )
-            );
-        }
-        foreach ($chapters as $chapter) {
-            list($ref_id, $chapter_id) = explode('_', $chapter);
 
+        foreach ($visibleChapters as $chapter) {
+            list($ref_id, $chapter_id) = explode('_', $chapter);
+            if (!in_array($chapter, $chapters)) {
+                $this->objectives_lm_obj->deleteMaterial($ref_id, $chapter_id);
+                continue;
+            }
+            if ($this->objectives_lm_obj->isMaterialAssigned($ref_id, $chapter_id)) {
+                continue;
+            }
             $this->objectives_lm_obj->setLMRefId($ref_id);
             $this->objectives_lm_obj->setLMObjId($chapter_id);
             $this->objectives_lm_obj->setType(ilLMObject::_lookupType($chapter_id));
diff --git a/Modules/Course/templates/default/tpl.crs_objective_list_materials_row.html b/Modules/Course/templates/default/tpl.crs_objective_list_materials_row.html
index 135ca7d2c6ec..433676ac2288 100644
--- a/Modules/Course/templates/default/tpl.crs_objective_list_materials_row.html
+++ b/Modules/Course/templates/default/tpl.crs_objective_list_materials_row.html
@@ -1,7 +1,8 @@
 <tr class="{CSS_ROW}">
 	<td class="std">
 		<input type="checkbox" name="materials[]" value="{VAL_ID}" id="{VAL_ID}" {VAL_CHECKED} />
-	</td>	
+		<input type="hidden" name="visible_materials[]" value="{VAL_ID}" />
+	</td>
 	<td class="std ilCenter">
   		<label for="{VAL_ID}">
 			<img class="ilIcon" src="{ROW_TYPE_IMG}" alt="{ROW_TYPE_ALT}" title="{ROW_TYPE_ALT}" />
@@ -20,7 +21,8 @@
 				<!--  BEGIN begin_depth --><div class="listIndent"><!--  END begin_depth -->
 				<li>
 					<input type="checkbox" name="chapters[]" value="{CHAP_ID}" id="{CHAP_ID}" {CHAP_CHECKED} />
-					<label for="{CHAP_ID}"> 
+					<input type="hidden" name="visible_chapters[]" value="{CHAP_ID}" />
+					<label for="{CHAP_ID}">
 						<img src="{CHAP_TYPE_IMG}" class="ilIcon" alt="{CHAP_TYPE_ALT}" title="{CHAP_TYPE_ALT}" />
 						{CHAPTER_TITLE}
 					</label>