diff --git a/app/controllers/concerns/lti.rb b/app/controllers/concerns/lti.rb
index 702327d1..0d8a86cc 100644
--- a/app/controllers/concerns/lti.rb
+++ b/app/controllers/concerns/lti.rb
@@ -15,19 +15,20 @@ module Lti
   end
   private :build_tool_provider
 
+  # exercise_id.nil? ==> the user has logged out. All session data is to be destroyed
+  # exercise_id.exists? ==> the user has submitted the results of an exercise to the consumer.
+  # Only the lti_parameters are deleted.
   def clear_lti_session_data(exercise_id = nil)
     #Todo replace session with lti_parameter /done
-    #TODO decide if we need to remove all LtiParameters for user/consumer
     if (exercise_id.nil?)
       LtiParameter.destroy_all(consumers_id: session[:consumer_id], external_user_id: session[:external_user_external_id])
-    else #TODO: probably it does not make sense to keep the LtiParameters if the session is deleted
+      session.delete(:consumer_id)
+      session.delete(:external_user_id)
+    else
       LtiParameter.destroy_all(consumers_id: session[:consumer_id],
                                external_user_id: session[:external_user_external_id],
                                exercises_id: exercise_id)
     end
-    session.delete(:consumer_id)
-    session.delete(:external_user_id)
-    #session.delete(:lti_parameters)
   end
   private :clear_lti_session_data
 
diff --git a/app/controllers/sessions_controller.rb b/app/controllers/sessions_controller.rb
index 9a9a7029..e99d0ad8 100644
--- a/app/controllers/sessions_controller.rb
+++ b/app/controllers/sessions_controller.rb
@@ -38,7 +38,6 @@ class SessionsController < ApplicationController
   def destroy_through_lti
     @consumer = Consumer.find_by(id: params[:consumer_id])
     @submission = Submission.find(params[:submission_id])
-    #TODO decide if we need to remove all LtiParameters for user/consumer
     clear_lti_session_data(@submission.exercise_id)
   end
 
diff --git a/app/views/sessions/destroy_through_lti.html.slim b/app/views/sessions/destroy_through_lti.html.slim
index 8f1e89a8..3e55e0fc 100644
--- a/app/views/sessions/destroy_through_lti.html.slim
+++ b/app/views/sessions/destroy_through_lti.html.slim
@@ -3,6 +3,7 @@ h1 = t('.headline')
 p
   == t(".success_#{params[:outcome] ? 'with' : 'without'}_outcome", consumer: @consumer)
   ==< t(".finished_#{@consumer ? 'with' : 'without'}_consumer", consumer: @consumer, url: params[:url])
+  ==< t(".do_not_use_backbutton", consumer: @consumer)
 
 h2 = t('shared.statistics')
 
diff --git a/config/locales/de.yml b/config/locales/de.yml
index 0695eda6..55fea63f 100644
--- a/config/locales/de.yml
+++ b/config/locales/de.yml
@@ -386,6 +386,7 @@ de:
       score: Ihre Punktzahl
       success_with_outcome: 'Ihr Code wurde erfolgreich bewertet. Ihre Bewertung wurde an %{consumer} übermittelt.'
       success_without_outcome: Ihr Code wurde erfolgreich bewertet.
+      do_not_use_backbutton: Benutzen Sie nicht den "Zurück" Button des Browsers, um zu CodeOcean zurück zu kehren. Übungen müssen immer aus dem %{consumer} Kontext gestartet werden.
     new:
       forgot_password: Passwort vergessen?
       headline: Anmelden
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 34ebd266..598faa33 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -407,6 +407,7 @@ en:
       score: Your Score
       success_with_outcome: 'Your code has been successfully assessed. Your grade has been transmitted to %{consumer}.'
       success_without_outcome: Your code has been successfully assessed.
+      do_not_use_backbutton: Never use the browser's "Back" button to get back to CodeOcean. Always start an exercise from within %{consumer}.
     new:
       forgot_password: Forgot password?
       headline: Sign In