diff --git a/app/assets/stylesheets/forms.css.scss b/app/assets/stylesheets/forms.css.scss
index fc7dd6d0..62613e8e 100644
--- a/app/assets/stylesheets/forms.css.scss
+++ b/app/assets/stylesheets/forms.css.scss
@@ -7,6 +7,13 @@
   width: 100% !important;
 }
 
+.chosen-inline {
+  .chosen-container {
+    min-width: unset !important;
+    width: unset !important;
+  }
+}
+
 .code-field {
   font-family: monospace;
 }
diff --git a/app/assets/stylesheets/statistics.css.scss b/app/assets/stylesheets/statistics.css.scss
index e636e9b0..f3f006eb 100644
--- a/app/assets/stylesheets/statistics.css.scss
+++ b/app/assets/stylesheets/statistics.css.scss
@@ -62,6 +62,18 @@ tr.highlight {
   border-top: 2px solid rgba(222,0,0,1);
 }
 
+.before_deadline {
+  background-color: #DAF7A6;
+}
+
+.within_grace_period {
+  background-color: #F7DC6F;
+}
+
+.after_late_deadline {
+  background-color: #EC7063;
+}
+
 /////////////////////////////////////////////////////////////////////////////////////////////
 // StatisticsController:
 
diff --git a/app/controllers/exercises_controller.rb b/app/controllers/exercises_controller.rb
index 2bb18096..b2242a01 100644
--- a/app/controllers/exercises_controller.rb
+++ b/app/controllers/exercises_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ExercisesController < ApplicationController
   include CommonBehavior
   include Lti
@@ -5,16 +7,16 @@ class ExercisesController < ApplicationController
   include SubmissionScoring
   include TimeHelper
 
-  before_action :handle_file_uploads, only: [:create, :update]
-  before_action :set_execution_environments, only: [:create, :edit, :new, :update]
-  before_action :set_exercise_and_authorize, only: MEMBER_ACTIONS + [:clone, :implement, :working_times, :intervention, :search, :run, :statistics, :submit, :reload, :feedback, :requests_for_comments, :study_group_dashboard, :export_external_check, :export_external_confirm]
+  before_action :handle_file_uploads, only: %i[create update]
+  before_action :set_execution_environments, only: %i[create edit new update]
+  before_action :set_exercise_and_authorize, only: MEMBER_ACTIONS + %i[clone implement working_times intervention search run statistics submit reload feedback requests_for_comments study_group_dashboard export_external_check export_external_confirm]
   before_action :set_external_user_and_authorize, only: [:statistics]
-  before_action :set_file_types, only: [:create, :edit, :new, :update]
+  before_action :set_file_types, only: %i[create edit new update]
   before_action :set_course_token, only: [:implement]
 
-  skip_before_action :verify_authenticity_token, only: [:import_exercise, :import_uuid_check, :export_external_confirm]
-  skip_after_action :verify_authorized, only: [:import_exercise, :import_uuid_check, :export_external_confirm]
-  skip_after_action :verify_policy_scoped, only: [:import_exercise, :import_uuid_check, :export_external_confirm], raise: false
+  skip_before_action :verify_authenticity_token, only: %i[import_exercise import_uuid_check export_external_confirm]
+  skip_after_action :verify_authorized, only: %i[import_exercise import_uuid_check export_external_confirm]
+  skip_after_action :verify_policy_scoped, only: %i[import_exercise import_uuid_check export_external_confirm], raise: false
 
   def authorize!
     authorize(@exercise || @exercises)
@@ -31,13 +33,13 @@ class ExercisesController < ApplicationController
 
   def experimental_courses
     {
-        java17: "702cbd2a-c84c-4b37-923a-692d7d1532d0",
-        java1: "0ea88ea9-979a-44a3-b0e4-84ba58e5a05e"
+      java17: '702cbd2a-c84c-4b37-923a-692d7d1532d0',
+      java1: '0ea88ea9-979a-44a3-b0e4-84ba58e5a05e'
     }
   end
 
   def experimental_course?(course_token)
-    experimental_courses.has_value?(course_token)
+    experimental_courses.value?(course_token)
   end
 
   def batch_update
@@ -76,18 +78,18 @@ class ExercisesController < ApplicationController
   def create
     @exercise = Exercise.new(exercise_params)
     collect_set_and_unset_exercise_tags
-    myparam = exercise_params.present? ? exercise_params : { }
-    checked_exercise_tags = @exercise_tags.select { | et | myparam[:tag_ids].include? et.tag.id.to_s }
-    removed_exercise_tags = @exercise_tags.reject { | et | myparam[:tag_ids].include? et.tag.id.to_s }
+    myparam = exercise_params.present? ? exercise_params : {}
+    checked_exercise_tags = @exercise_tags.select { |et| myparam[:tag_ids].include? et.tag.id.to_s }
+    removed_exercise_tags = @exercise_tags.reject { |et| myparam[:tag_ids].include? et.tag.id.to_s }
 
-    for et in checked_exercise_tags
+    checked_exercise_tags.each do |et|
       et.factor = params[:tag_factors][et.tag_id.to_s][:factor]
       et.exercise = @exercise
     end
 
     myparam[:exercise_tags] = checked_exercise_tags
     myparam.delete :tag_ids
-    removed_exercise_tags.map {|et| et.destroy}
+    removed_exercise_tags.map(&:destroy)
 
     authorize!
     create_and_respond(object: @exercise)
@@ -112,12 +114,12 @@ class ExercisesController < ApplicationController
   def requests_for_comments
     authorize!
     @search = RequestForComment
-                  .with_last_activity
-                  .where(exercise: @exercise)
-                  .ransack(params[:q])
+              .with_last_activity
+              .where(exercise: @exercise)
+              .ransack(params[:q])
     @request_for_comments = @search.result
-                                .order('last_comment DESC')
-                                .paginate(page: params[:page])
+                                   .order('last_comment DESC')
+                                   .paginate(page: params[:page])
     render 'request_for_comments/index'
   end
 
@@ -210,7 +212,7 @@ class ExercisesController < ApplicationController
   private :user_by_codeharbor_token
 
   def exercise_params
-    params[:exercise].permit(:description, :execution_environment_id, :file_id, :instructions, :public, :unpublished, :hide_file_tree, :allow_file_creation, :allow_auto_completion, :title, :expected_difficulty, files_attributes: file_attributes, :tag_ids => []).merge(user_id: current_user.id, user_type: current_user.class.name) if params[:exercise].present?
+    params[:exercise].permit(:description, :execution_environment_id, :file_id, :instructions, :submission_deadline, :late_submission_deadline, :public, :unpublished, :hide_file_tree, :allow_file_creation, :allow_auto_completion, :title, :expected_difficulty, files_attributes: file_attributes, tag_ids: []).merge(user_id: current_user.id, user_type: current_user.class.name) if params[:exercise].present?
   end
   private :exercise_params
 
@@ -232,56 +234,55 @@ class ExercisesController < ApplicationController
   private :handle_file_uploads
 
   def implement
-    redirect_to(@exercise, alert: t('exercises.implement.unpublished')) if @exercise.unpublished? && current_user.role != 'admin' && current_user.role != 'teacher' # TODO TESTESTEST
+    redirect_to(@exercise, alert: t('exercises.implement.unpublished')) if @exercise.unpublished? && current_user.role != 'admin' && current_user.role != 'teacher' # TODO: TESTESTEST
     redirect_to(@exercise, alert: t('exercises.implement.no_files')) unless @exercise.files.visible.exists?
     user_solved_exercise = @exercise.has_user_solved(current_user)
-    count_interventions_today = UserExerciseIntervention.where(user: current_user).where("created_at >= ?", Time.zone.now.beginning_of_day).count
+    count_interventions_today = UserExerciseIntervention.where(user: current_user).where('created_at >= ?', Time.zone.now.beginning_of_day).count
     user_got_intervention_in_exercise = UserExerciseIntervention.where(user: current_user, exercise: @exercise).size >= max_intervention_count_per_exercise
-    user_got_enough_interventions = count_interventions_today >= max_intervention_count_per_day or user_got_intervention_in_exercise
+    (user_got_enough_interventions = count_interventions_today >= max_intervention_count_per_day) || user_got_intervention_in_exercise
 
-    unless @embed_options[:disable_interventions]
-      @show_rfc_interventions = (not user_solved_exercise and not user_got_enough_interventions).to_s
+    if @embed_options[:disable_interventions]
+      @show_rfc_interventions = false
       @show_break_interventions = false
     else
-      @show_rfc_interventions = false
+      @show_rfc_interventions = (!user_solved_exercise && !user_got_enough_interventions).to_s
       @show_break_interventions = false
     end
 
     @hide_rfc_button = @embed_options[:disable_rfc]
 
-
     @search = Search.new
     @search.exercise = @exercise
     @submission = current_user.submissions.where(exercise_id: @exercise.id).order('created_at DESC').first
     @files = (@submission ? @submission.collect_files : @exercise.files).select(&:visible).sort_by(&:name_with_extension)
     @paths = collect_paths(@files)
 
-    if current_user.respond_to? :external_id
-      @user_id = current_user.external_id
-    else
-      @user_id = current_user.id
-    end
+    @user_id = if current_user.respond_to? :external_id
+                 current_user.external_id
+               else
+                 current_user.id
+               end
   end
 
   def set_course_token
     lti_parameters = LtiParameter.where(external_users_id: current_user.id,
-                                          exercises_id: @exercise.id).last
+                                        exercises_id: @exercise.id).last
     if lti_parameters
-      lti_json = lti_parameters.lti_parameters["launch_presentation_return_url"]
+      lti_json = lti_parameters.lti_parameters['launch_presentation_return_url']
 
       @course_token =
-          unless lti_json.nil?
-            if match = lti_json.match(/^.*courses\/([a-z0-9\-]+)\/sections/)
-              match.captures.first
-            else
-              ""
-            end
+        if lti_json.nil?
+          ''
+        else
+          if match = lti_json.match(%r{^.*courses/([a-z0-9\-]+)/sections})
+            match.captures.first
           else
-            ""
+            ''
           end
+        end
     else
       # no consumer, therefore implementation with internal user
-      @course_token = "702cbd2a-c84c-4b37-923a-692d7d1532d0"
+      @course_token = '702cbd2a-c84c-4b37-923a-692d7d1532d0'
     end
   end
   private :set_course_token
@@ -294,14 +295,15 @@ class ExercisesController < ApplicationController
 
   def intervention
     intervention = Intervention.find_by_name(params[:intervention_type])
-    unless intervention.nil?
+    if intervention.nil?
+      render(json: {success: 'false', error: "undefined intervention #{params[:intervention_type]}"})
+    else
       uei = UserExerciseIntervention.new(
-          user: current_user, exercise: @exercise, intervention: intervention,
-          accumulated_worktime_s: @exercise.accumulated_working_time_for_only(current_user))
+        user: current_user, exercise: @exercise, intervention: intervention,
+        accumulated_worktime_s: @exercise.accumulated_working_time_for_only(current_user)
+      )
       uei.save
       render(json: {success: 'true'})
-    else
-      render(json: {success: 'false', error: "undefined intervention #{params[:intervention_type]}"})
     end
   end
 
@@ -310,9 +312,9 @@ class ExercisesController < ApplicationController
     search = Search.new(user: current_user, exercise: @exercise, search: search_text)
 
     begin search.save
-      render(json: {success: 'true'})
-    rescue
-      render(json: {success: 'false', error: "could not save search: #{$!}"})
+          render(json: {success: 'true'})
+    rescue StandardError
+      render(json: {success: 'false', error: "could not save search: #{$ERROR_INFO}"})
     end
   end
 
@@ -386,9 +388,9 @@ class ExercisesController < ApplicationController
     @search = policy_scope(Tag).ransack(params[:q])
     @tags = @search.result.order(:name)
     checked_exercise_tags = @exercise.exercise_tags
-    checked_tags = checked_exercise_tags.collect{|e| e.tag}.to_set
+    checked_tags = checked_exercise_tags.collect(&:tag).to_set
     unchecked_tags = Tag.all.to_set.subtract checked_tags
-    @exercise_tags = checked_exercise_tags + unchecked_tags.collect { |tag| ExerciseTag.new(exercise: @exercise, tag: tag)}
+    @exercise_tags = checked_exercise_tags + unchecked_tags.collect { |tag| ExerciseTag.new(exercise: @exercise, tag: tag) }
   end
   private :collect_set_and_unset_exercise_tags
 
@@ -401,27 +403,39 @@ class ExercisesController < ApplicationController
   end
 
   def statistics
-    if(@external_user)
+    if @external_user
       authorize(@external_user, :statistics?)
-      @submissions = Submission.where("user_id = ?  AND exercise_id = ?", @external_user.id, @exercise.id).order("created_at")
-      interventions = UserExerciseIntervention.where("user_id = ?  AND exercise_id = ?", @external_user.id, @exercise.id)
-      @all_events = (@submissions + interventions).sort_by { |a| a.created_at }
-      @deltas = @all_events.map.with_index do |item, index|
-        delta = item.created_at - @all_events[index - 1].created_at if index > 0
-        if delta == nil or delta > StatisticsHelper::WORKING_TIME_DELTA_IN_SECONDS then 0 else delta end
-      end
-      @working_times_until = []
-      @all_events.each_with_index do |_, index|
-        @working_times_until.push((format_time_difference(@deltas[0..index].inject(:+)) if index > 0))
+      if policy(@exercise).detailed_statistics?
+        @submissions = Submission.where(user: @external_user, exercise_id: @exercise.id).in_study_group_of(current_user).order('created_at')
+        interventions = UserExerciseIntervention.where('user_id = ?  AND exercise_id = ?', @external_user.id, @exercise.id)
+        @all_events = (@submissions + interventions).sort_by(&:created_at)
+        @deltas = @all_events.map.with_index do |item, index|
+          delta = item.created_at - @all_events[index - 1].created_at if index > 0
+          delta.nil? || (delta > StatisticsHelper::WORKING_TIME_DELTA_IN_SECONDS) ? 0 : delta
+        end
+        @working_times_until = []
+        @all_events.each_with_index do |_, index|
+          @working_times_until.push((format_time_difference(@deltas[0..index].inject(:+)) if index > 0))
+        end
+      else
+        latest_submissions = Submission.where(user: @external_user, exercise_id: @exercise.id).in_study_group_of(current_user).final.latest
+        relevant_submissions = latest_submissions.before_deadline.or(latest_submissions.within_grace_period).or(latest_submissions.after_late_deadline)
+        @submissions = relevant_submissions.sort_by(&:created_at)
+        @all_events = @submissions
       end
       render 'exercises/external_users/statistics'
     else
       user_statistics = {}
+      additional_filter = if policy(@exercise).detailed_statistics?
+                            ''
+                          else
+                            "AND study_group_id IN (#{current_user.study_groups.pluck(:id).join(', ')}) AND cause = 'submit'"
+                          end
       query = "SELECT user_id, MAX(score) AS maximum_score, COUNT(id) AS runs
-              FROM submissions WHERE exercise_id = #{@exercise.id} GROUP BY
+              FROM submissions WHERE exercise_id = #{@exercise.id} #{additional_filter} GROUP BY
               user_id;"
       ApplicationRecord.connection.execute(query).each do |tuple|
-        user_statistics[tuple["user_id"].to_i] = tuple
+        user_statistics[tuple['user_id'].to_i] = tuple
       end
       render locals: {
         user_statistics: user_statistics
@@ -441,7 +455,7 @@ class ExercisesController < ApplicationController
   end
 
   def transmit_lti_score
-    ::NewRelic::Agent.add_custom_attributes({ submission: @submission.id, normalized_score: @submission.normalized_score })
+    ::NewRelic::Agent.add_custom_attributes({submission: @submission.id, normalized_score: @submission.normalized_score})
     response = send_score(@submission.exercise_id, @submission.normalized_score, @submission.user_id)
 
     if response[:status] == 'success'
@@ -458,17 +472,17 @@ class ExercisesController < ApplicationController
   def update
     collect_set_and_unset_exercise_tags
     myparam = exercise_params
-    checked_exercise_tags = @exercise_tags.select { | et | myparam[:tag_ids].include? et.tag.id.to_s }
-    removed_exercise_tags = @exercise_tags.reject { | et | myparam[:tag_ids].include? et.tag.id.to_s }
+    checked_exercise_tags = @exercise_tags.select { |et| myparam[:tag_ids].include? et.tag.id.to_s }
+    removed_exercise_tags = @exercise_tags.reject { |et| myparam[:tag_ids].include? et.tag.id.to_s }
 
-    for et in checked_exercise_tags
+    checked_exercise_tags.each do |et|
       et.factor = params[:tag_factors][et.tag_id.to_s][:factor]
       et.exercise = @exercise
     end
 
     myparam[:exercise_tags] = checked_exercise_tags
     myparam.delete :tag_ids
-    removed_exercise_tags.map {|et| et.destroy}
+    removed_exercise_tags.map(&:destroy)
     update_and_respond(object: @exercise, params: myparam)
   end
 
@@ -511,21 +525,21 @@ class ExercisesController < ApplicationController
 
           clear_lti_session_data(@submission.exercise_id, @submission.user_id, session[:consumer_id])
           respond_to do |format|
-            format.html {redirect_to(rfc)}
-            format.json {render(json: {redirect: url_for(rfc)})}
+            format.html { redirect_to(rfc) }
+            format.json { render(json: {redirect: url_for(rfc)}) }
           end
           return
         end
       end
     else
       # redirect to feedback page if score is less than 100 percent
-       if @exercise.needs_more_feedback? && !@embed_options[:disable_redirect_to_feedback]
-         clear_lti_session_data(@submission.exercise_id, @submission.user_id, session[:consumer_id])
-         redirect_to_user_feedback
-       else
-         redirect_to_lti_return_path
-       end
-       return
+      if @exercise.needs_more_feedback? && !@embed_options[:disable_redirect_to_feedback]
+        clear_lti_session_data(@submission.exercise_id, @submission.user_id, session[:consumer_id])
+        redirect_to_user_feedback
+      else
+        redirect_to_lti_return_path
+      end
+      return
     end
     redirect_to_lti_return_path
   end
@@ -547,12 +561,11 @@ class ExercisesController < ApplicationController
   def study_group_dashboard
     authorize!
     @study_group_id = params[:study_group_id]
-    @request_for_comments = RequestForComment.
-            where(exercise: @exercise).includes(:submission).
-            where(submissions: {study_group_id: @study_group_id}).
-            order(created_at: :desc)
+    @request_for_comments = RequestForComment
+                            .where(exercise: @exercise).includes(:submission)
+                            .where(submissions: {study_group_id: @study_group_id})
+                            .order(created_at: :desc)
 
     @graph_data = @exercise.get_working_times_for_study_group(@study_group_id)
   end
-
 end
diff --git a/app/controllers/external_users_controller.rb b/app/controllers/external_users_controller.rb
index 537631f6..a7d39341 100644
--- a/app/controllers/external_users_controller.rb
+++ b/app/controllers/external_users_controller.rb
@@ -6,7 +6,7 @@ class ExternalUsersController < ApplicationController
 
   def index
     @search = ExternalUser.ransack(params[:q])
-    @users = @search.result.includes(:consumer).paginate(page: params[:page])
+    @users = @search.result.in_study_group_of(current_user).includes(:consumer).paginate(page: params[:page])
     authorize!
   end
 
@@ -41,6 +41,7 @@ class ExternalUsersController < ApplicationController
           FROM submissions
           WHERE user_id = #{@user.id}
             AND user_type = 'ExternalUser'
+          #{!current_user.admin? ? "AND study_group_id IN (#{current_user.study_groups.pluck(:id).join(', ')}) AND cause = 'submit'" : ''}
           GROUP BY exercise_id,
                    user_id,
                    id
diff --git a/app/models/exercise.rb b/app/models/exercise.rb
index 86b402d8..74e8a477 100644
--- a/app/models/exercise.rb
+++ b/app/models/exercise.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 require 'nokogiri'
-require File.expand_path('../../../lib/active_model/validations/boolean_presence_validator', __FILE__)
+require File.expand_path('../../lib/active_model/validations/boolean_presence_validator', __dir__)
 
 class Exercise < ApplicationRecord
   include Context
@@ -25,11 +27,12 @@ class Exercise < ApplicationRecord
 
   has_many :external_users, source: :user, source_type: 'ExternalUser', through: :submissions
   has_many :internal_users, source: :user, source_type: 'InternalUser', through: :submissions
-  alias_method :users, :external_users
+  alias users external_users
 
   scope :with_submissions, -> { where('id IN (SELECT exercise_id FROM submissions)') }
 
   validate :valid_main_file?
+  validate :valid_submission_deadlines?
   validates :description, presence: true
   validates :execution_environment, presence: true, if: -> { !unpublished? }
   validates :public, boolean_presence: true
@@ -44,7 +47,7 @@ class Exercise < ApplicationRecord
   MAX_EXERCISE_FEEDBACKS = 20
 
   def average_percentage
-    if average_score and maximum_score != 0.0 and submissions.exists?(cause: 'submit')
+    if average_score && (maximum_score != 0.0) && submissions.exists?(cause: 'submit')
       (average_score / maximum_score * 100).round(2)
     else
       0
@@ -68,11 +71,13 @@ class Exercise < ApplicationRecord
 
   def average_number_of_submissions
     user_count = internal_users.distinct.count + external_users.distinct.count
-    return user_count == 0 ? 0 : submissions.count() / user_count.to_f()
+    user_count == 0 ? 0 : submissions.count / user_count.to_f
   end
 
   def time_maximum_score(user)
-    submissions.where(user: user).where("cause IN ('submit','assess')").where("score IS NOT NULL").order("score DESC, created_at ASC").first.created_at rescue Time.zone.at(0)
+    submissions.where(user: user).where("cause IN ('submit','assess')").where('score IS NOT NULL').order('score DESC, created_at ASC').first.created_at
+  rescue StandardError
+    Time.zone.at(0)
   end
 
   def user_working_time_query
@@ -100,7 +105,7 @@ class Exercise < ApplicationRecord
   end
 
   def study_group_working_time_query(exercise_id, study_group_id, additional_filter)
-    """
+    ''"
     WITH working_time_between_submissions AS (
       SELECT submissions.user_id,
          submissions.user_type,
@@ -193,7 +198,7 @@ class Exercise < ApplicationRecord
     FROM working_times_with_index
        JOIN internal_users ON user_type = 'InternalUser' AND user_id = internal_users.id
     ORDER BY index, score ASC;
-    """
+    "''
   end
 
   def get_working_times_for_study_group(study_group_id, user = nil)
@@ -202,36 +207,34 @@ class Exercise < ApplicationRecord
     max_bucket = 100
     maximum_score = self.maximum_score
 
-    if user.blank?
-      additional_filter = ''
-    else
-      additional_filter = "AND user_id = #{user.id} AND user_type = '#{user.class.name}'"
-    end
+    additional_filter = if user.blank?
+                          ''
+                        else
+                          "AND user_id = #{user.id} AND user_type = '#{user.class.name}'"
+                        end
 
     results = self.class.connection.execute(study_group_working_time_query(id, study_group_id, additional_filter)).each do |tuple|
-      if maximum_score > 0.0 && tuple['score'] <= maximum_score
-        bucket = (tuple['score'] / maximum_score * max_bucket).round
-      else
-        bucket = max_bucket # maximum_score / maximum_score will always be 1
-      end
+      bucket = if maximum_score > 0.0 && tuple['score'] <= maximum_score
+                 (tuple['score'] / maximum_score * max_bucket).round
+               else
+                 max_bucket # maximum_score / maximum_score will always be 1
+               end
 
       user_progress[bucket] ||= []
       additional_user_data[bucket] ||= []
       additional_user_data[max_bucket + 1] ||= []
 
-      user_progress[bucket][tuple['index']] = tuple["working_time_per_score"]
-      additional_user_data[bucket][tuple['index']] = {start_time: tuple["start_time"], score: tuple["score"]}
+      user_progress[bucket][tuple['index']] = tuple['working_time_per_score']
+      additional_user_data[bucket][tuple['index']] = {start_time: tuple['start_time'], score: tuple['score']}
       additional_user_data[max_bucket + 1][tuple['index']] = {id: tuple['user_id'], type: tuple['user_type'], name: tuple['name']}
     end
 
     if results.ntuples > 0
       first_index = results[0]['index']
-      last_index = results[results.ntuples-1]['index']
+      last_index = results[results.ntuples - 1]['index']
       buckets = last_index - first_index
       user_progress.each do |timings_array|
-        if timings_array.present? && timings_array.length != buckets + 1
-          timings_array[buckets] = nil
-        end
+        timings_array[buckets] = nil if timings_array.present? && timings_array.length != buckets + 1
       end
     end
 
@@ -239,8 +242,8 @@ class Exercise < ApplicationRecord
   end
 
   def get_quantiles(quantiles)
-    quantiles_str = "[" + quantiles.join(",") + "]"
-    result = self.class.connection.execute("""
+    quantiles_str = '[' + quantiles.join(',') + ']'
+    result = self.class.connection.execute(''"
             WITH working_time AS
       (
                SELECT   user_id,
@@ -346,13 +349,12 @@ class Exercise < ApplicationRecord
                         exercise_id )
       SELECT   unnest(percentile_cont(array#{quantiles_str}) within GROUP (ORDER BY working_time))
       FROM     result
-    """)
+    "'')
     if result.count > 0
-      quantiles.each_with_index.map{|q,i| Time.parse(result[i]["unnest"]).seconds_since_midnight}
+      quantiles.each_with_index.map { |_q, i| Time.parse(result[i]['unnest']).seconds_since_midnight }
     else
-      quantiles.map{|q| 0}
+      quantiles.map { |_q| 0 }
     end
-
   end
 
   def retrieve_working_time_statistics
@@ -363,72 +365,74 @@ class Exercise < ApplicationRecord
   end
 
   def average_working_time
-    self.class.connection.execute("""
+    self.class.connection.execute(''"
       SELECT avg(working_time) as average_time
       FROM
         (#{user_working_time_query}) AS baz;
-    """).first['average_time']
+    "'').first['average_time']
   end
 
   def average_working_time_for(user_id)
-    if @working_time_statistics == nil
-      retrieve_working_time_statistics()
-    end
-    @working_time_statistics[user_id]["working_time"]
+    retrieve_working_time_statistics if @working_time_statistics.nil?
+    @working_time_statistics[user_id]['working_time']
   end
 
   def accumulated_working_time_for_only(user)
-    user_type = user.external_user? ? "ExternalUser" : "InternalUser"
-    Time.parse(self.class.connection.execute("""
-        WITH WORKING_TIME AS
-        (SELECT user_id,
-                           id,
-                           exercise_id,
-                           max(score) AS max_score,
-                           (created_at - lag(created_at) OVER (PARTITION BY user_id, exercise_id
-                                                               ORDER BY created_at)) AS working_time
-                   FROM submissions
-                   WHERE exercise_id = #{id} AND user_id = #{user.id} AND user_type = '#{user_type}'
-                   GROUP BY user_id, id, exercise_id),
-        MAX_POINTS AS
-        (SELECT context_id AS ex_id, sum(weight) AS max_points FROM files WHERE context_type = 'Exercise' AND context_id = #{id} AND role = 'teacher_defined_test' GROUP BY context_id),
+    user_type = user.external_user? ? 'ExternalUser' : 'InternalUser'
+    begin
+      Time.parse(self.class.connection.execute(''"
+              WITH WORKING_TIME AS
+              (SELECT user_id,
+                                 id,
+                                 exercise_id,
+                                 max(score) AS max_score,
+                                 (created_at - lag(created_at) OVER (PARTITION BY user_id, exercise_id
+                                                                     ORDER BY created_at)) AS working_time
+                         FROM submissions
+                         WHERE exercise_id = #{id} AND user_id = #{user.id} AND user_type = '#{user_type}'
+                         GROUP BY user_id, id, exercise_id),
+              MAX_POINTS AS
+              (SELECT context_id AS ex_id, sum(weight) AS max_points FROM files WHERE context_type = 'Exercise' AND context_id = #{id} AND role = 'teacher_defined_test' GROUP BY context_id),
 
-        -- filter for rows containing max points
-        TIME_MAX_SCORE AS
-        (SELECT *
-        FROM WORKING_TIME W1, MAX_POINTS MS
-        WHERE W1.exercise_id = ex_id AND W1.max_score = MS.max_points),
+              -- filter for rows containing max points
+              TIME_MAX_SCORE AS
+              (SELECT *
+              FROM WORKING_TIME W1, MAX_POINTS MS
+              WHERE W1.exercise_id = ex_id AND W1.max_score = MS.max_points),
 
-        -- find row containing the first time max points
-        FIRST_TIME_MAX_SCORE AS
-        ( SELECT id,USER_id,exercise_id,max_score,working_time, rn
-          FROM (
-            SELECT id,USER_id,exercise_id,max_score,working_time,
-                ROW_NUMBER() OVER(PARTITION BY user_id, exercise_id ORDER BY id ASC) AS rn
-            FROM TIME_MAX_SCORE) T
-         WHERE rn = 1),
+              -- find row containing the first time max points
+              FIRST_TIME_MAX_SCORE AS
+              ( SELECT id,USER_id,exercise_id,max_score,working_time, rn
+                FROM (
+                  SELECT id,USER_id,exercise_id,max_score,working_time,
+                      ROW_NUMBER() OVER(PARTITION BY user_id, exercise_id ORDER BY id ASC) AS rn
+                  FROM TIME_MAX_SCORE) T
+               WHERE rn = 1),
 
-        TIMES_UNTIL_MAX_POINTS AS (
-            SELECT W.id, W.user_id, W.exercise_id, W.max_score, W.working_time, M.id AS reachedmax_at
-            FROM WORKING_TIME W, FIRST_TIME_MAX_SCORE M
-            WHERE W.user_id = M.user_id AND W.exercise_id = M.exercise_id AND W.id <= M.id),
+              TIMES_UNTIL_MAX_POINTS AS (
+                  SELECT W.id, W.user_id, W.exercise_id, W.max_score, W.working_time, M.id AS reachedmax_at
+                  FROM WORKING_TIME W, FIRST_TIME_MAX_SCORE M
+                  WHERE W.user_id = M.user_id AND W.exercise_id = M.exercise_id AND W.id <= M.id),
 
-        -- if user never makes it to max points, take all times
-        ALL_WORKING_TIMES_UNTIL_MAX AS
-        ((SELECT id, user_id, exercise_id, max_score, working_time FROM TIMES_UNTIL_MAX_POINTS)
-        UNION ALL
-        (SELECT id, user_id, exercise_id, max_score, working_time FROM WORKING_TIME W1
-         WHERE NOT EXISTS (SELECT 1 FROM FIRST_TIME_MAX_SCORE F WHERE F.user_id = W1.user_id AND F.exercise_id = W1.exercise_id))),
+              -- if user never makes it to max points, take all times
+              ALL_WORKING_TIMES_UNTIL_MAX AS
+              ((SELECT id, user_id, exercise_id, max_score, working_time FROM TIMES_UNTIL_MAX_POINTS)
+              UNION ALL
+              (SELECT id, user_id, exercise_id, max_score, working_time FROM WORKING_TIME W1
+               WHERE NOT EXISTS (SELECT 1 FROM FIRST_TIME_MAX_SCORE F WHERE F.user_id = W1.user_id AND F.exercise_id = W1.exercise_id))),
 
-        FILTERED_TIMES_UNTIL_MAX AS
-        (
-        SELECT user_id,exercise_id, max_score, CASE WHEN working_time >= #{StatisticsHelper::WORKING_TIME_DELTA_IN_SQL_INTERVAL} THEN '0' ELSE working_time END AS working_time_new
-        FROM ALL_WORKING_TIMES_UNTIL_MAX
-        )
-            SELECT e.external_id AS external_user_id, f.user_id, exercise_id, MAX(max_score) AS max_score, sum(working_time_new) AS working_time
-            FROM FILTERED_TIMES_UNTIL_MAX f, EXTERNAL_USERS e
-            WHERE f.user_id = e.id GROUP BY e.external_id, f.user_id, exercise_id
-    """).first["working_time"]).seconds_since_midnight rescue 0
+              FILTERED_TIMES_UNTIL_MAX AS
+              (
+              SELECT user_id,exercise_id, max_score, CASE WHEN working_time >= #{StatisticsHelper::WORKING_TIME_DELTA_IN_SQL_INTERVAL} THEN '0' ELSE working_time END AS working_time_new
+              FROM ALL_WORKING_TIMES_UNTIL_MAX
+              )
+                  SELECT e.external_id AS external_user_id, f.user_id, exercise_id, MAX(max_score) AS max_score, sum(working_time_new) AS working_time
+                  FROM FILTERED_TIMES_UNTIL_MAX f, EXTERNAL_USERS e
+                  WHERE f.user_id = e.id GROUP BY e.external_id, f.user_id, exercise_id
+          "'').first['working_time']).seconds_since_midnight
+    rescue StandardError
+      0
+    end
   end
 
   def duplicate(attributes = {})
@@ -453,7 +457,8 @@ class Exercise < ApplicationRecord
       return 'main_file'
     elsif (file_class == 'internal') && (comment == 'main')
     end
-    return 'regular_file'
+
+    'regular_file'
   end
 
   def from_proforma_xml(xml_string)
@@ -467,23 +472,23 @@ class Exercise < ApplicationRecord
       description: description,
       instructions: description
     }
-    task_node.xpath('p:files/p:file').all? { |file|
+    task_node.xpath('p:files/p:file').all? do |file|
       file_name_split = file.xpath('@filename').first.value.split('.')
       file_class = file.xpath('@class').first.value
       role = determine_file_role_from_proforma_file(task_node, file)
-      feedback_message_nodes = task_node.xpath("p:tests/p:test/p:test-configuration/c:feedback-message/text()")
+      feedback_message_nodes = task_node.xpath('p:tests/p:test/p:test-configuration/c:feedback-message/text()')
       files.build({
-        name: file_name_split.first,
-        content: file.xpath('text()').first.content,
-        read_only: false,
-        hidden: file_class == 'internal',
-        role: role,
-        feedback_message: (role == 'teacher_defined_test') ? feedback_message_nodes.first.content : nil,
-        file_type: FileType.where(
-          file_extension: ".#{file_name_split.second}"
-        ).take
-      })
-    }
+                    name: file_name_split.first,
+                    content: file.xpath('text()').first.content,
+                    read_only: false,
+                    hidden: file_class == 'internal',
+                    role: role,
+                    feedback_message: role == 'teacher_defined_test' ? feedback_message_nodes.first.content : nil,
+                    file_type: FileType.where(
+                      file_extension: ".#{file_name_split.second}"
+                    ).take
+                  })
+    end
     self.execution_environment_id = 1
   end
 
@@ -495,7 +500,11 @@ class Exercise < ApplicationRecord
   def maximum_score(user = nil)
     if user
       # FIXME: where(user: user) will not work here!
-      submissions.where(user: user).where("cause IN ('submit','assess')").where("score IS NOT NULL").order("score DESC").first.score || 0 rescue 0
+      begin
+        submissions.where(user: user).where("cause IN ('submit','assess')").where('score IS NOT NULL').order('score DESC').first.score || 0
+      rescue StandardError
+        0
+      end
     else
       files.teacher_defined_tests.sum(:weight)
     end
@@ -510,7 +519,7 @@ class Exercise < ApplicationRecord
   end
 
   def finishers
-    ExternalUser.joins(:submissions).where(submissions: {exercise_id: id, score: maximum_score, cause: %w(submit assess)}).distinct
+    ExternalUser.joins(:submissions).where(submissions: {exercise_id: id, score: maximum_score, cause: %w[submit assess]}).distinct
   end
 
   def set_default_values
@@ -523,12 +532,22 @@ class Exercise < ApplicationRecord
   end
 
   def valid_main_file?
-    if files.main_files.count > 1
-      errors.add(:files, I18n.t('activerecord.errors.models.exercise.at_most_one_main_file'))
-    end
+    errors.add(:files, I18n.t('activerecord.errors.models.exercise.at_most_one_main_file')) if files.main_files.count > 1
   end
   private :valid_main_file?
 
+  def valid_submission_deadlines?
+    return unless submission_deadline.present? || late_submission_deadline.present?
+
+    errors.add(:late_submission_deadline, I18n.t('activerecord.errors.models.exercise.late_submission_deadline_not_alone')) if late_submission_deadline.present? && submission_deadline.blank?
+
+    if submission_deadline.present? && late_submission_deadline.present? &&
+       late_submission_deadline < submission_deadline
+      errors.add(:late_submission_deadline, I18n.t('activerecord.errors.models.exercise.late_submission_deadline_not_before_submission_deadline'))
+    end
+  end
+  private :valid_submission_deadlines?
+
   def needs_more_feedback?
     user_exercise_feedbacks.size <= MAX_EXERCISE_FEEDBACKS
   end
@@ -543,5 +562,4 @@ class Exercise < ApplicationRecord
           WHERE exercise_id = #{id}
         ) AS t ON t.fv = submissions.id").distinct
   end
-
 end
diff --git a/app/models/submission.rb b/app/models/submission.rb
index 60f865e9..dc0f2eae 100644
--- a/app/models/submission.rb
+++ b/app/models/submission.rb
@@ -15,11 +15,22 @@ class Submission < ApplicationRecord
   has_many :structured_errors
   has_many :comments, through: :files
 
+  belongs_to :external_users, -> { where(submissions: {user_type: 'ExternalUser'}).includes(:submissions) }, foreign_key: :user_id, class_name: 'ExternalUser', optional: true
+  belongs_to :internal_users, -> { where(submissions: {user_type: 'InternalUser'}).includes(:submissions) }, foreign_key: :user_id, class_name: 'InternalUser', optional: true
+
   delegate :execution_environment, to: :exercise
 
   scope :final, -> { where(cause: 'submit') }
   scope :intermediate, -> { where.not(cause: 'submit') }
 
+  scope :before_deadline, -> { joins(:exercise).where('submissions.updated_at <= exercises.submission_deadline OR exercises.submission_deadline IS NULL') }
+  scope :within_grace_period, -> { joins(:exercise).where('(submissions.updated_at > exercises.submission_deadline) AND (submissions.updated_at <= exercises.late_submission_deadline OR exercises.late_submission_deadline IS NULL)') }
+  scope :after_late_deadline, -> { joins(:exercise).where('submissions.updated_at > exercises.late_submission_deadline') }
+
+  scope :latest, -> { order(updated_at: :desc).limit(1) }
+
+  scope :in_study_group_of, ->(user) { where(study_group_id: user.study_groups) unless user.admin? }
+
   validates :cause, inclusion: {in: CAUSES}
   validates :exercise_id, presence: true
 
@@ -29,6 +40,7 @@ class Submission < ApplicationRecord
   def build_files_hash(files, attribute)
     files.map(&attribute.to_proc).zip(files).to_h
   end
+
   private :build_files_hash
 
   def collect_files
@@ -42,7 +54,7 @@ class Submission < ApplicationRecord
   end
 
   def normalized_score
-    ::NewRelic::Agent.add_custom_attributes({ unnormalized_score: score })
+    ::NewRelic::Agent.add_custom_attributes({unnormalized_score: score})
     if !score.nil? && !exercise.maximum_score.nil? && (exercise.maximum_score > 0)
       score / exercise.maximum_score
     else
@@ -62,6 +74,32 @@ class Submission < ApplicationRecord
     Submission.model_name.human
   end
 
+  def before_deadline?
+    if exercise.submission_deadline.present?
+      updated_at <= exercise.submission_deadline
+    else
+      false
+    end
+  end
+
+  def within_grace_period?
+    if exercise.submission_deadline.present? && exercise.late_submission_deadline.present?
+      updated_at > exercise.submission_deadline && updated_at <= exercise.late_submission_deadline
+    else
+      false
+    end
+  end
+
+  def after_late_deadline?
+    if exercise.late_submission_deadline.present?
+      updated_at > exercise.late_submission_deadline
+    elsif exercise.submission_deadline.present?
+      updated_at > exercise.submission_deadline
+    else
+      false
+    end
+  end
+
   def redirect_to_feedback?
     ((user_id + exercise.created_at.to_i) % 10 == 1) && exercise.needs_more_feedback?
   end
@@ -71,6 +109,6 @@ class Submission < ApplicationRecord
   end
 
   def unsolved_rfc
-    RequestForComment.unsolved.where(exercise_id: exercise).where.not(question: nil).where(created_at: OLDEST_RFC_TO_SHOW.ago..Time.current).order("RANDOM()").find { | rfc_element |( (rfc_element.comments_count < MAX_COMMENTS_ON_RECOMMENDED_RFC) && (!rfc_element.question.empty?)) }
+    RequestForComment.unsolved.where(exercise_id: exercise).where.not(question: nil).where(created_at: OLDEST_RFC_TO_SHOW.ago..Time.current).order("RANDOM()").find { |rfc_element| ((rfc_element.comments_count < MAX_COMMENTS_ON_RECOMMENDED_RFC) && (!rfc_element.question.empty?)) }
   end
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index 73b21fe0..031dd464 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -19,6 +19,8 @@ class User < ApplicationRecord
 
   scope :with_submissions, -> { where('id IN (SELECT user_id FROM submissions)') }
 
+  scope :in_study_group_of, ->(user) { joins(:study_group_memberships).where(study_group_memberships: {study_group_id: user.study_groups}) unless user.admin? }
+
   ROLES.each do |role|
     define_method("#{role}?") { try(:role) == role }
   end
diff --git a/app/policies/application_policy.rb b/app/policies/application_policy.rb
index 5bd92946..a162c368 100644
--- a/app/policies/application_policy.rb
+++ b/app/policies/application_policy.rb
@@ -33,9 +33,14 @@ class ApplicationPolicy
       users_in_same_study_group = study_group.users
     elsif @record.respond_to? :users # e.g. study_group
       users_in_same_study_group = @record.users
-    else # e.g. exercise
+    elsif @record.respond_to? :user # e.g. exercise
       study_groups = @record.user.study_groups
       users_in_same_study_group = study_groups.collect(&:users).flatten
+    elsif @record.respond_to? :study_groups # e.g. user
+      study_groups = @record.study_groups
+      users_in_same_study_group = study_groups.collect(&:users).flatten
+    else
+      return false
     end
 
     users_in_same_study_group.include? @user
diff --git a/app/policies/exercise_policy.rb b/app/policies/exercise_policy.rb
index a5fab334..083f6952 100644
--- a/app/policies/exercise_policy.rb
+++ b/app/policies/exercise_policy.rb
@@ -11,6 +11,14 @@ class ExercisePolicy < AdminOrAuthorPolicy
     admin? || teacher_in_study_group?
   end
 
+  def submission_statistics?
+    admin? || teacher_in_study_group?
+  end
+
+  def detailed_statistics?
+    admin?
+  end
+
   [:clone?, :destroy?, :edit?, :update?, :export_external_check?, :export_external_confirm?].each do |action|
     define_method(action) { admin? || teacher_in_study_group? || author? }
   end
diff --git a/app/policies/external_user_policy.rb b/app/policies/external_user_policy.rb
index 4257fa4b..c35b1eb5 100644
--- a/app/policies/external_user_policy.rb
+++ b/app/policies/external_user_policy.rb
@@ -1,6 +1,14 @@
 class ExternalUserPolicy < AdminOnlyPolicy
+  def index?
+    admin? || teacher?
+  end
+
+  def show?
+    admin? || teacher_in_study_group?
+  end
+
   def statistics?
-    admin?
+    admin? || teacher_in_study_group?
   end
 
   def tag_statistics?
diff --git a/app/views/exercises/_form.html.slim b/app/views/exercises/_form.html.slim
index dcf31568..aaa4800b 100644
--- a/app/views/exercises/_form.html.slim
+++ b/app/views/exercises/_form.html.slim
@@ -16,6 +16,16 @@
     = f.label(:instructions)
     = f.hidden_field(:instructions)
     .form-control.markdown
+  .form-group
+    = f.label(:submission_deadline)
+    .chosen-inline
+      = f.datetime_select(:submission_deadline, include_blank: true)
+    .help-block.form-text == t('.hints.submission_deadline')
+  .form-group
+    = f.label(:late_submission_deadline)
+    .chosen-inline
+      = f.datetime_select(:late_submission_deadline, include_blank: true)
+    .help-block.form-text == t('.hints.late_submission_deadline')
   .form-check
     label.form-check-label
       = f.check_box(:public, class: 'form-check-input')
diff --git a/app/views/exercises/external_users/statistics.html.slim b/app/views/exercises/external_users/statistics.html.slim
index 5e8a79ae..61ac33b0 100644
--- a/app/views/exercises/external_users/statistics.html.slim
+++ b/app/views/exercises/external_users/statistics.html.slim
@@ -1,4 +1,4 @@
-h1 = "#{@exercise} (external user #{link_to_if(policy(@external_user).show?, @external_user.displayname, @external_user)})"
+h1 = "#{@exercise} (external user #{link_to_if(policy(@external_user).show?, @external_user.displayname, @external_user)})".html_safe
 - current_submission = @submissions.first
 - if current_submission
   - initial_files = current_submission.files.to_a
@@ -36,32 +36,54 @@ h1 = "#{@exercise} (external user #{link_to_if(policy(@external_user).show?, @ex
       table.table
         thead
           tr
-            - ['.time', '.cause', '.score', '.tests', '.time_difference'].each do |title|
-              th.header = t(title)
+            th.header = t('.time')
+            th.header = t('.cause')
+            th.header = t('.score')
+            th.header = t('.tests')
+            th.header = t('.time_difference') if policy(@exercise).detailed_statistics?
         tbody
           - @all_events.each_with_index do |this, index|
             - highlight = (index > 0 and @deltas[index] == 0 and this.created_at.to_s != @all_events[index - 1].created_at.to_s)
-            tr data-id=this.id class=('highlight' if highlight)
+            - row_classes = ''
+            - row_classes += ' highlight' if highlight
+            - row_classes += ' before_deadline' if this.is_a?(Submission) && this.before_deadline?
+            - row_classes += ' within_grace_period' if this.is_a?(Submission) && this.within_grace_period?
+            - row_classes += ' after_late_deadline' if this.is_a?(Submission) && this.after_late_deadline?
+            tr data-id=this.id class=row_classes
               td.clickable = this.created_at.strftime("%F %T")
               - if this.is_a?(Submission)
                 td = this.cause
                 td = this.score
-                td
+                td.align-middle
                   -this.testruns.each do |run|
                     - if run.passed
                       .unit-test-result.positive-result title=run.output
                     - else
                       .unit-test-result.unknown-result title=run.output
-                td = @working_times_until[index] if index > 0
+                td = @working_times_until[index] if index > 0 if policy(@exercise).detailed_statistics?
               - elsif this.is_a? UserExerciseIntervention
                 td = this.intervention.name
                 td =
                 td =
-                td = @working_times_until[index] if index > 0
-    p = t('.addendum', delta: StatisticsHelper::WORKING_TIME_DELTA_IN_SECONDS / 60)
-    .d-none#wtimes data-working_times=ActiveSupport::JSON.encode(@working_times_until);
-    div#progress_chart.col-lg-12
-      .graph-functions-2
+                td = @working_times_until[index] if index > 0 if policy(@exercise).detailed_statistics?
+    small
+      b
+        = t('.legend')
+      .container.px-0.border
+        .row.w-100.mx-0
+          .col-sm-3.py-2
+            = t('.no_deadline')
+          .col-sm-3.before_deadline.py-2
+            = t('.before_deadline')
+          .col-sm-3.within_grace_period.py-2
+            = t('.within_grace_period')
+          .col-sm-3.after_late_deadline.py-2
+            = t('.after_late_deadline')
+    - if current_user.try(:admin?)
+      p = t('.addendum', delta: StatisticsHelper::WORKING_TIME_DELTA_IN_SECONDS / 60)
+      .d-none#wtimes data-working_times=ActiveSupport::JSON.encode(@working_times_until);
+      div#progress_chart.col-lg-12
+        .graph-functions-2
 
 - else
   p = t('.no_data_available')
diff --git a/app/views/exercises/show.html.slim b/app/views/exercises/show.html.slim
index 832b13f9..f9d2b6a2 100644
--- a/app/views/exercises/show.html.slim
+++ b/app/views/exercises/show.html.slim
@@ -25,6 +25,8 @@ h1
 = row(label: 'exercise.execution_environment', value: link_to_if(@exercise.execution_environment && policy(@exercise.execution_environment).show?, @exercise.execution_environment, @exercise.execution_environment))
 /= row(label: 'exercise.instructions', value: render_markdown(@exercise.instructions))
 = row(label: 'exercise.maximum_score', value: @exercise.maximum_score)
+= row(label: 'exercise.submission_deadline', value: @exercise.submission_deadline)
+= row(label: 'exercise.late_submission_deadline', value: @exercise.late_submission_deadline)
 = row(label: 'exercise.public', value: @exercise.public?)
 = row(label: 'exercise.unpublished', value: @exercise.unpublished?)
 = row(label: 'exercise.hide_file_tree', value: @exercise.hide_file_tree?)
diff --git a/app/views/exercises/statistics.html.slim b/app/views/exercises/statistics.html.slim
index d4b7b1b2..2f80ee7e 100644
--- a/app/views/exercises/statistics.html.slim
+++ b/app/views/exercises/statistics.html.slim
@@ -25,12 +25,13 @@ h1 = @exercise
   p = @exercise.average_working_time
 
 - Hash[:internal_users => t('.internal_users'), :external_users => t('.external_users')].each_pair do |symbol, label|
-  strong = label
-  -if symbol==:external_users
-    -working_time_array = []
+  - if symbol==:internal_users && current_user.admin?
+    strong = label
+  - if symbol==:external_users
+    - working_time_array = []
     - @exercise.send(symbol).distinct().each do |user|
-      -working_time = @exercise.average_working_time_for(user.id) or 0
-      -working_time_array.push working_time
+      - working_time = @exercise.average_working_time_for(user.id) or 0
+      - working_time_array.push working_time
     hr
     .d-none#data data-working-time=ActiveSupport::JSON.encode(working_time_array)
     .working-time-graphs
@@ -38,19 +39,26 @@ h1 = @exercise
     hr
     div#chart_2
     hr
-  - if current_user.admin?
+  - submissions = Submission.where(user: @exercise.send(symbol).distinct, exercise: @exercise).in_study_group_of(current_user)
+  - if !policy(@exercise).detailed_statistics?
+    - submissions = submissions.final
+  - any_viewable_submission = submissions.first
+  - if any_viewable_submission
     .table-responsive
       table.table.table-striped.sortable
         thead
           tr
-            - ['.user', '.score', '.runs', '.worktime'].each do |title|
-              th.header = t(title)
+            th.header = t('.user')
+            th.header = t('.score')
+            th.header = t('.runs') if policy(@exercise).detailed_statistics?
+            th.header = t('.worktime') if policy(@exercise).detailed_statistics?
         tbody
-          - @exercise.send(symbol).distinct().each do |user|
+          - users = symbol.to_s.classify.constantize.where(id: submissions.joins(symbol).group(:user_id).select(:user_id).distinct)
+          - users.each do |user|
             - if user_statistics[user.id] then us = user_statistics[user.id] else us = {"maximum_score" => nil, "runs" => nil}
             - label = "#{user.displayname}"
             tr
               td = link_to_if symbol==:external_users && policy(user).statistics?, label, {controller: "exercises", action: "statistics", external_user_id: user.id, id: @exercise.id}
               td = us['maximum_score'] or 0
-              td = us['runs']
-              td = @exercise.average_working_time_for(user.id) or 0
+              td = us['runs'] if policy(@exercise).detailed_statistics?
+              td = @exercise.average_working_time_for(user.id) or 0 if policy(@exercise).detailed_statistics?
diff --git a/app/views/external_users/show.html.slim b/app/views/external_users/show.html.slim
index b3f72d6c..1f1ad756 100644
--- a/app/views/external_users/show.html.slim
+++ b/app/views/external_users/show.html.slim
@@ -1,7 +1,7 @@
 h1 = @user.displayname
 
 = row(label: 'external_user.name', value: @user.name)
-= row(label: 'external_user.email', value: @user.email)
+= row(label: 'external_user.email', value: @user.email) if current_user.admin?
 = row(label: 'external_user.external_id') do
   code
     = @user.external_id
@@ -10,10 +10,11 @@ h1 = @user.displayname
 
 h4.mt-4 = link_to(t('.exercise_statistics'), statistics_external_user_path(@user)) if policy(@user).statistics?
 
-h4.mt-4 = t('.tag_statistics')
-#loading
-  .spinner
-  = t('.loading_tag_statistics')
-#no-elements
-  = t('.empty_tag_statistics')
-#tag-grid
+- if current_user.admin?
+  h4.mt-4 = t('.tag_statistics')
+  #loading
+    .spinner
+    = t('.loading_tag_statistics')
+  #no-elements
+    = t('.empty_tag_statistics')
+  #tag-grid
diff --git a/app/views/external_users/statistics.html.slim b/app/views/external_users/statistics.html.slim
index 368846a8..a7e78887 100644
--- a/app/views/external_users/statistics.html.slim
+++ b/app/views/external_users/statistics.html.slim
@@ -1,19 +1,30 @@
 h1 = t('.title')
 
-- exercises = Exercise.where(:id => @user.submissions.group(:exercise_id).select(:exercise_id).distinct)
+- submissions = Submission.where(user: @user).in_study_group_of(current_user)
+- exercises = Exercise.where(id: submissions.joins(:exercise).group(:exercise_id).select(:exercise_id).distinct)
+- if !policy(exercises.first).detailed_statistics?
+  - submissions = submissions.final
+- any_viewable_submission = submissions.first
 
-.table-responsive
-  table.table.table-striped.sortable
-    thead
-      tr
-        - ['.exercise', '.score', '.runs', '.worktime'].each do |title|
-          th.header = t(title)
-    tbody
-      - exercises.each do |exercise|
-        - if statistics[exercise.id]
-          - stats = statistics[exercise.id]
-          tr
-            td = link_to_if policy(exercise).show?, exercise, controller: "exercises", action: "statistics", external_user_id: @user.id, id: exercise.id
-            td = stats["maximum_score"] or 0
-            td = stats["runs"] or 0
-            td = stats["working_time"] or 0
+- if any_viewable_submission && policy(any_viewable_submission).show_study_group?
+  .table-responsive
+    table.table.table-striped.sortable
+      thead
+        tr
+          th.header = t('.exercise')
+          th.header = t('.score')
+          th.header = t('.runs') if policy(exercises.first).detailed_statistics?
+          th.header = t('.worktime') if policy(exercises.first).detailed_statistics?
+      tbody
+        - exercises.each do |exercise|
+          // Grab any submission in context of study group (or all if admin). Then check for permission
+          - any_submission = submissions.where(exercise: exercise).first
+          - if any_submission && policy(any_submission).show_study_group? && statistics[exercise.id]
+            - stats = statistics[exercise.id]
+            tr
+              td = link_to exercise, controller: "exercises", action: "statistics", external_user_id: @user.id, id: exercise.id
+              td = stats["maximum_score"] or 0
+              td = stats["runs"] or 0 if policy(exercises.first).detailed_statistics?
+              td = stats["working_time"] or 0 if policy(exercises.first).detailed_statistics?
+- else
+  = t('exercises.external_users.statistics.no_data_available')
\ No newline at end of file
diff --git a/config/locales/de.yml b/config/locales/de.yml
index 208e573b..5d5ab495 100644
--- a/config/locales/de.yml
+++ b/config/locales/de.yml
@@ -35,6 +35,8 @@ de:
         hide_file_tree: Dateibaum verstecken
         instructions: Anweisungen
         maximum_score: Erreichbare Punktzahl
+        submission_deadline: Abgabefrist
+        late_submission_deadline: Verspätete Abgabefrist
         number_of_users: "# Nutzer"
         public: Öffentlich
         selection: Ausgewählt
@@ -216,6 +218,8 @@ de:
       models:
         exercise:
           at_most_one_main_file: dürfen höchstens eine Hauptdatei enthalten
+          late_submission_deadline_not_alone: darf nicht ohne eine reguläre Abgabefrist verwendet werden
+          late_submission_deadline_not_before_submission_deadline: darf nicht vor der reguläre Abgabefrist liegen
   admin:
     dashboard:
       show:
@@ -347,6 +351,9 @@ de:
       unpublish_warning: Mit dieser Aktion wird die Aufgabe deaktiviert. Jeder Student, der versucht sie zu implementieren wird eine Fehlermeldung bekommen, bis die Aufgabe wieder aktiviert wurde.
       no_execution_environment_selected: Bitte eine Ausführungsumgebung auswählen, bevor die Aufgabe aktiviert wird.
       none: Keine
+      hints:
+        submission_deadline: Ein Zeitpunkt in UTC, zu dem die Abgabe geschlossen wird. Einreichungen nach der Abgabefrist werden als verspätet gekennzeichnet.
+        late_submission_deadline: Eine Gnadenfrist für Abgaben in UTC. Die verlängerte Abgabefrist soll nicht vor der eigentlichen Abgabefrist liegen. Nachdem die Gnadenfrist verstichen ist, werden keine neuen Einreichungen mehr akzeptiert.
     implement:
       alert:
         text: 'Ihr Browser unterstützt nicht alle Funktionalitäten, die %{application_name} benötigt. Bitte nutzen Sie einen modernen Browser, um %{application_name} zu besuchen.'
@@ -406,7 +413,7 @@ de:
       participants: Bearbeitende Nutzer
       users: '%{count} verschiedene Nutzer'
       user: Nutzer
-      score: Punktzahl
+      score: Maximale Punktzahl
       runs: Versuche
       worktime: Arbeitszeit
       average_worktime: Durchschnittliche Arbeitszeit
@@ -426,12 +433,17 @@ de:
       no_data_yet: Bisher sind keine Daten verfügbar
     external_users:
       statistics:
-        no_data_available: Keine Daten verfügbar.
+        no_data_available: Keine Daten verfügbar oder fehlende Berechtigungen.
         time: Zeit
         cause: Grund
         score: Punktzahl
         tests: Unit Tests
         time_difference: 'Arbeitszeit bis hier*'
+        legend: 'Legende:'
+        no_deadline: Keine Abgabefrist
+        before_deadline: Abgabe rechtzeitig
+        within_grace_period: Abgabe innerhalb der Gnadenfrist
+        after_late_deadline: Verspätete Abgabe
         addendum: '* Differenzen von mehr als %{delta} Minuten werden ignoriert.'
   proxy_exercises:
       index:
@@ -440,7 +452,7 @@ de:
     statistics:
       title: Statistiken für Externe Benutzer
       exercise: Übung
-      score: Bewertung
+      score: Maximale Punktzahl
       runs: Abgaben
       worktime: Arbeitszeit
     show:
diff --git a/config/locales/en.yml b/config/locales/en.yml
index d3d805bd..dd8edc97 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -35,6 +35,8 @@ en:
         hide_file_tree: Hide File Tree
         instructions: Instructions
         maximum_score: Maximum Score
+        submission_deadline: Submission Deadline
+        late_submission_deadline: Late Submission Deadline
         number_of_users: "# Users"
         public: Public
         selection: Selected
@@ -216,6 +218,8 @@ en:
       models:
         exercise:
           at_most_one_main_file: must include at most one main file
+          late_submission_deadline_not_alone: must not be used without a regular submission deadline
+          late_submission_deadline_not_before_submission_deadline: must not be before the submission deadline passed
   admin:
     dashboard:
       show:
@@ -347,6 +351,9 @@ en:
       unpublish_warning: This will unpublish the exercise. Any student trying to implement it will get an error message, until it is published again.
       no_execution_environment_selected: Select an execution environment before publishing the exercise.
       none: None
+      hints:
+        submission_deadline: A date and time in UTC to close the submission. Any submission obtained after the deadline will be considered late.
+        late_submission_deadline: A grace period for submissions in UTC. The late submission deadline should not be set or any timestamp before the original submission deadline. After the late submission deadline passed, any new submissions are prevented.
     implement:
       alert:
         text: 'Your browser does not support features required for using %{application_name}. Please access %{application_name} using a modern browser.'
@@ -406,7 +413,7 @@ en:
       participants: Participating Users
       users: '%{count} distinct users'
       user: User
-      score: Score
+      score: Maximum Score
       runs: Runs
       worktime: Working Time
       average_worktime: Average Working Time
@@ -426,12 +433,17 @@ en:
       no_data_yet: No data available yet
     external_users:
       statistics:
-        no_data_available: No data available.
+        no_data_available: No data available or insufficient permissions
         time: Time
         cause: Cause
         score: Score
         tests: Unit Test Results
         time_difference: 'Working Time until here*'
+        legend: 'Legend:'
+        no_deadline: No Deadline
+        before_deadline: On Time
+        within_grace_period: Within Grace Period
+        after_late_deadline: Too Late
         addendum: "* Deltas longer than %{delta} minutes are ignored."
   proxy_exercises:
       index:
@@ -440,7 +452,7 @@ en:
     statistics:
       title: External User Statistics
       exercise: Exercise
-      score: Score
+      score: Maximum Score
       runs: Submissions
       worktime: Working Time
     show:
diff --git a/db/migrate/20200506093054_add_deadline_to_exercises.rb b/db/migrate/20200506093054_add_deadline_to_exercises.rb
new file mode 100644
index 00000000..39526198
--- /dev/null
+++ b/db/migrate/20200506093054_add_deadline_to_exercises.rb
@@ -0,0 +1,6 @@
+class AddDeadlineToExercises < ActiveRecord::Migration[5.2]
+  def change
+    add_column :exercises, :submission_deadline, :datetime, null: true, default: nil
+    add_column :exercises, :late_submission_deadline, :datetime, null: true, default: nil
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 54992b77..bbc6bc60 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_03_26_115249) do
+ActiveRecord::Schema.define(version: 2020_05_06_093054) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -154,6 +154,8 @@ ActiveRecord::Schema.define(version: 2020_03_26_115249) do
     t.integer "expected_difficulty", default: 1
     t.uuid "uuid"
     t.boolean "unpublished", default: false
+    t.datetime "submission_deadline"
+    t.datetime "late_submission_deadline"
     t.index ["id"], name: "index_exercises_on_id"
   end
 
@@ -423,5 +425,6 @@ ActiveRecord::Schema.define(version: 2020_03_26_115249) do
     t.index ["user_type", "user_id"], name: "index_user_proxy_exercise_exercises_on_user_type_and_user_id"
   end
 
+  add_foreign_key "request_for_comments", "submissions", name: "request_for_comments_submissions_id_fk"
   add_foreign_key "submissions", "study_groups"
 end
diff --git a/spec/policies/external_user_policy_spec.rb b/spec/policies/external_user_policy_spec.rb
index d668c305..5d1e468c 100644
--- a/spec/policies/external_user_policy_spec.rb
+++ b/spec/policies/external_user_policy_spec.rb
@@ -3,7 +3,7 @@ require 'rails_helper'
 describe ExternalUserPolicy do
   subject { described_class }
 
-  [:create?, :destroy?, :edit?, :index?, :new?, :show?, :update?].each do |action|
+  [:create?, :destroy?, :edit?, :new?, :show?, :update?].each do |action|
     permissions(action) do
       it 'grants access to admins only' do
         expect(subject).to permit(FactoryBot.build(:admin), ExternalUser.new)
@@ -13,4 +13,16 @@ describe ExternalUserPolicy do
       end
     end
   end
+
+  [:index?].each do |action|
+    permissions(action) do
+      it 'grants access to admins and teachers only' do
+        expect(subject).to permit(FactoryBot.build(:admin), ExternalUser.new)
+        expect(subject).to permit(FactoryBot.build(:teacher), ExternalUser.new)
+        [:external_user].each do |factory_name|
+          expect(subject).not_to permit(FactoryBot.build(factory_name), ExternalUser.new)
+        end
+      end
+    end
+  end
 end