diff --git a/.gitignore b/.gitignore
index 4e183355..89d0de42 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@
 /rubocop.html
 /tmp
 /vagrant/
+/.vagrant
 *.sublime-*
 /.idea
 /.vagrant
diff --git a/Gemfile.lock b/Gemfile.lock
index c257ca70..5972ea79 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -388,6 +388,3 @@ DEPENDENCIES
   uglifier (>= 1.3.0)
   web-console (~> 2.0)
   will_paginate (~> 3.0)
-
-BUNDLED WITH
-   1.10.6
diff --git a/app/assets/javascripts/submission_statistics.js b/app/assets/javascripts/submission_statistics.js
new file mode 100644
index 00000000..75fe42cd
--- /dev/null
+++ b/app/assets/javascripts/submission_statistics.js
@@ -0,0 +1,96 @@
+$(function() {
+
+  var ACE_FILES_PATH = '/assets/ace/';
+  var THEME = 'ace/theme/textmate';
+
+  var currentSubmission = 0;
+  var active_file = undefined;
+  var fileTrees = []
+  var editor = undefined;
+  var fileTypeById = {}
+
+  var showActiveFile = function() {
+    var session = editor.getSession();
+    var fileType = fileTypeById[active_file.file_type_id]
+    session.setMode(fileType.editor_mode);
+    session.setTabSize(fileType.indent_size);
+    session.setValue(active_file.content);
+    session.setUseSoftTabs(true);
+    session.setUseWrapMode(true);
+
+    showFileTree(currentSubmission);
+    filetree = $(fileTrees[currentSubmission])
+    filetree.jstree("deselect_all");
+    filetree.jstree().select_node(active_file.file_id);
+  };
+
+  var initializeFileTree = function() {
+    $('.files').each(function(index, element) {
+      fileTree = $(element).jstree($(element).data('entries'));
+      fileTree.on('click', 'li.jstree-leaf', function() {
+        var id = parseInt($(this).attr('id'))
+        _.each(files[currentSubmission], function(file) {
+          if (file.file_id === id) {
+            active_file = file;
+          }
+        });
+        showActiveFile();
+      });
+      fileTrees.push(fileTree);
+    });
+  };
+
+  var showFileTree = function(index) {
+    $('.files').hide();
+    $(fileTrees[index].context).show();
+  }
+
+  if ($.isController('exercises') && $('#timeline').isPresent()) {
+
+    _.each(['modePath', 'themePath', 'workerPath'], function(attribute) {
+      ace.config.set(attribute, ACE_FILES_PATH);
+    });
+
+    var slider = $('#submissions-slider>input');
+    var submissions = $('#data').data('submissions');
+    var files = $('#data').data('files');
+    var filetypes = $('#data').data('file-types');
+
+    editor = ace.edit('current-file');
+    editor.setShowPrintMargin(false);
+    editor.setTheme(THEME);
+    editor.$blockScrolling = Infinity;
+    editor.setReadOnly(true);
+
+    _.each(filetypes, function (filetype) {
+      filetype = JSON.parse(filetype);
+      fileTypeById[filetype.id] = filetype;
+    });
+
+    $('tr[data-id]>.clickable').each(function(index, element) {
+      element = $(element);
+      element.click(function() {
+        slider.val(index);
+        slider.change()
+      });
+    });
+
+    slider.on('change', function(event) {
+      currentSubmission = slider.val();
+      var currentFiles = files[currentSubmission];
+      var fileIndex = 0;
+      _.each(currentFiles, function(file, index) {
+        if (file.name === active_file.name) {
+          fileIndex = index;
+        }
+      })
+      active_file = currentFiles[fileIndex];
+      showActiveFile();
+    });
+
+    active_file = files[0][0]
+    initializeFileTree();
+    showActiveFile();
+  }
+
+});
diff --git a/app/assets/stylesheets/statistics.css.scss b/app/assets/stylesheets/statistics.css.scss
new file mode 100644
index 00000000..d148f782
--- /dev/null
+++ b/app/assets/stylesheets/statistics.css.scss
@@ -0,0 +1,12 @@
+#submissions-slider {
+    margin-top: 25px;
+    margin-bottom: 25px;
+}
+
+#current-file.editor {
+    height: 400px;
+}
+
+.clickable {
+    cursor: pointer;
+}
diff --git a/app/controllers/execution_environments_controller.rb b/app/controllers/execution_environments_controller.rb
index 5e69f8fc..574aaed7 100644
--- a/app/controllers/execution_environments_controller.rb
+++ b/app/controllers/execution_environments_controller.rb
@@ -2,7 +2,7 @@ class ExecutionEnvironmentsController < ApplicationController
   include CommonBehavior
 
   before_action :set_docker_images, only: [:create, :edit, :new, :update]
-  before_action :set_execution_environment, only: MEMBER_ACTIONS + [:execute_command, :shell]
+  before_action :set_execution_environment, only: MEMBER_ACTIONS + [:execute_command, :shell, :statistics]
   before_action :set_testing_framework_adapters, only: [:create, :edit, :new, :update]
 
   def authorize!
@@ -28,6 +28,9 @@ class ExecutionEnvironmentsController < ApplicationController
     render(json: @docker_client.execute_arbitrary_command(params[:command]))
   end
 
+  def statistics
+  end
+
   def execution_environment_params
     params[:execution_environment].permit(:docker_image, :exposed_ports, :editor_mode, :file_extension, :file_type_id, :help, :indent_size, :memory_limit, :name, :network_enabled, :permitted_execution_time, :pool_size, :run_command, :test_command, :testing_framework).merge(user_id: current_user.id, user_type: current_user.class.name)
   end
diff --git a/app/controllers/exercises_controller.rb b/app/controllers/exercises_controller.rb
index 7a26627a..4f5e5b81 100644
--- a/app/controllers/exercises_controller.rb
+++ b/app/controllers/exercises_controller.rb
@@ -7,6 +7,7 @@ class ExercisesController < ApplicationController
   before_action :handle_file_uploads, only: [:create, :update]
   before_action :set_execution_environments, only: [:create, :edit, :new, :update]
   before_action :set_exercise, only: MEMBER_ACTIONS + [:clone, :implement, :run, :statistics, :submit, :reload]
+  before_action :set_external_user, only: [:statistics]
   before_action :set_file_types, only: [:create, :edit, :new, :update]
   before_action :set_teams, only: [:create, :edit, :new, :update]
 
@@ -125,6 +126,14 @@ class ExercisesController < ApplicationController
   end
   private :set_exercise
 
+  def set_external_user
+    if params[:external_user_id]
+      @external_user = ExternalUser.find(params[:external_user_id])
+      authorize!
+    end
+  end
+  private :set_exercise
+
   def set_file_types
     @file_types = FileType.all.order(:name)
   end
@@ -143,6 +152,11 @@ class ExercisesController < ApplicationController
   end
 
   def statistics
+    if(@external_user)
+      render 'exercises/external_users/statistics'
+    else
+      render 'exercises/statistics'
+    end
   end
 
   def submit
diff --git a/app/controllers/external_users_controller.rb b/app/controllers/external_users_controller.rb
index 1d22dc58..26af4fbf 100644
--- a/app/controllers/external_users_controller.rb
+++ b/app/controllers/external_users_controller.rb
@@ -13,4 +13,10 @@ class ExternalUsersController < ApplicationController
     @user = ExternalUser.find(params[:id])
     authorize!
   end
+
+  def statistics
+    @user = ExternalUser.find(params[:id])
+    authorize!
+  end
+
 end
diff --git a/app/models/exercise.rb b/app/models/exercise.rb
index 152d79bf..192c4513 100644
--- a/app/models/exercise.rb
+++ b/app/models/exercise.rb
@@ -11,7 +11,10 @@ class Exercise < ActiveRecord::Base
   belongs_to :execution_environment
   has_many :submissions
   belongs_to :team
-  has_many :users, source_type: ExternalUser, through: :submissions
+
+  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
 
   scope :with_submissions, -> { where('id IN (SELECT exercise_id FROM submissions)') }
 
@@ -22,15 +25,54 @@ class Exercise < ActiveRecord::Base
   validates :title, presence: true
   validates :token, presence: true, uniqueness: true
 
+
   def average_percentage
-    (average_score/ maximum_score * 100).round if average_score
+    (average_score / maximum_score * 100).round if average_score
   end
 
   def average_score
     if submissions.exists?(cause: 'submit')
       maximum_scores_query = submissions.select('MAX(score) AS maximum_score').where(cause: 'submit').group(:user_id).to_sql.sub('$1', id.to_s)
       self.class.connection.execute("SELECT AVG(maximum_score) AS average_score FROM (#{maximum_scores_query}) AS maximum_scores").first['average_score'].to_f
-    end
+    else 0 end
+  end
+
+  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()
+  end
+
+  def user_working_time_query
+    """
+      SELECT user_id,
+             sum(working_time_new) AS working_time
+      FROM
+        (SELECT user_id,
+                CASE WHEN working_time >= '0:30:00' THEN '0' ELSE working_time END AS working_time_new
+         FROM
+            (SELECT user_id,
+                    id,
+                    (created_at - lag(created_at) over (PARTITION BY user_id
+                                                        ORDER BY id)) AS working_time
+            FROM submissions
+            WHERE exercise_id=#{id}) AS foo) AS bar
+      GROUP BY user_id
+    """
+  end
+
+  def average_working_time
+    self.class.connection.execute("""
+      SELECT avg(working_time) as average_time
+      FROM
+        (#{user_working_time_query}) AS baz;
+    """).first['average_time']
+  end
+
+  def average_working_time_for(user_id)
+    self.class.connection.execute("""
+      #{user_working_time_query}
+      HAVING user_id = #{user_id}
+    """).first['working_time']
   end
 
   def duplicate(attributes = {})
diff --git a/app/policies/execution_environment_policy.rb b/app/policies/execution_environment_policy.rb
index 3766f714..bccc9a07 100644
--- a/app/policies/execution_environment_policy.rb
+++ b/app/policies/execution_environment_policy.rb
@@ -4,7 +4,7 @@ class ExecutionEnvironmentPolicy < AdminOrAuthorPolicy
   end
   private :author?
 
-  [:execute_command?, :shell?].each do |action|
+  [:execute_command?, :shell?, :statistics?].each do |action|
     define_method(action) { admin? || author? }
   end
 end
diff --git a/app/policies/external_user_policy.rb b/app/policies/external_user_policy.rb
index 6f638a8e..2e11060b 100644
--- a/app/policies/external_user_policy.rb
+++ b/app/policies/external_user_policy.rb
@@ -1,2 +1,5 @@
 class ExternalUserPolicy < AdminOnlyPolicy
+  def statistics?
+    admin?
+  end
 end
diff --git a/app/views/execution_environments/index.html.slim b/app/views/execution_environments/index.html.slim
index 3043be9d..dc30898f 100644
--- a/app/views/execution_environments/index.html.slim
+++ b/app/views/execution_environments/index.html.slim
@@ -10,7 +10,7 @@ h1 = ExecutionEnvironment.model_name.human(count: 2)
         th = t('activerecord.attributes.execution_environment.memory_limit')
         th = t('activerecord.attributes.execution_environment.network_enabled')
         th = t('activerecord.attributes.execution_environment.permitted_execution_time')
-        th colspan=4 = t('shared.actions')
+        th colspan=5 = t('shared.actions')
         th colspan=2 = t('shared.resources')
     tbody
       - @execution_environments.each do |execution_environment|
@@ -25,6 +25,7 @@ h1 = ExecutionEnvironment.model_name.human(count: 2)
           td = link_to(t('shared.edit'), edit_execution_environment_path(execution_environment))
           td = link_to(t('shared.destroy'), execution_environment, data: {confirm: t('shared.confirm_destroy')}, method: :delete)
           td = link_to(t('.shell'), shell_execution_environment_path(execution_environment))
+          td = link_to(t('shared.statistics'), statistics_execution_environment_path(execution_environment))
           td = link_to(t('activerecord.models.error.other'), execution_environment_errors_path(execution_environment.id))
           td = link_to(t('activerecord.models.hint.other'), execution_environment_hints_path(execution_environment.id))
 
diff --git a/app/views/execution_environments/statistics.html.slim b/app/views/execution_environments/statistics.html.slim
new file mode 100644
index 00000000..57579476
--- /dev/null
+++ b/app/views/execution_environments/statistics.html.slim
@@ -0,0 +1,15 @@
+h1 = @execution_environment
+
+.table-responsive
+  table.table
+    thead
+      tr
+        - ['.exercise', '.score', '.runs', '.worktime'].each do |title|
+          th.header = t(title)
+    tbody
+      - @execution_environment.exercises.each do |exercise|
+        tr
+          td = link_to exercise.title, controller: "exercises", action: "statistics", id: exercise.id
+          td = exercise.average_score
+          td = exercise.average_number_of_submissions
+          td = exercise.average_working_time
diff --git a/app/views/exercises/external_users/statistics.html.slim b/app/views/exercises/external_users/statistics.html.slim
new file mode 100644
index 00000000..ca5142cc
--- /dev/null
+++ b/app/views/exercises/external_users/statistics.html.slim
@@ -0,0 +1,48 @@
+h1 = "#{@exercise} (external user #{@external_user})"
+- submissions = Submission.where("user_id = ?  AND exercise_id = ?", @external_user.id, @exercise.id)
+- current_submission = submissions.first
+- if current_submission
+  - initial_files = current_submission.files.to_a
+
+  - all_files = []
+  - file_types = Set.new()
+  - submissions.each do |submission|
+    - submission.files.each do |file|
+      - file_types.add(ActiveSupport::JSON.encode(file.file_type))
+    - all_files.push(submission.files)
+
+  .hidden#data data-submissions=ActiveSupport::JSON.encode(submissions) data-files=ActiveSupport::JSON.encode(all_files) data-file-types=ActiveSupport::JSON.encode(file_types)
+
+  #stats-editor.row
+    - index = 0
+    - all_files.each do |files|
+      .files class=(@exercise.hide_file_tree ? 'hidden col-sm-3' : 'col-sm-3') data-index=index data-entries=FileTree.new(files).to_js_tree
+      - index += 1
+    div class=(@exercise.hide_file_tree ? 'col-sm-12' : 'col-sm-9')
+      #current-file.editor
+
+  #submissions-slider
+    input type='range' orient='horizontal' list='datapoints' min=0 max=submissions.length-1 value=0
+    datalist#datapoints
+      - index=0
+      - submissions.each do |submission|
+        option data-submission=submission
+          =index
+        - index += 1
+
+  #timeline
+    .table-responsive
+      table.table
+        thead
+          tr
+            - ['.time', '.cause', '.score'].each do |title|
+              th.header = t(title)
+        tbody
+          - submissions.each do |submission|
+            tr data-id=submission.id
+              td.clickable = submission.created_at.strftime("%F %T")
+              td = submission.cause
+              td = submission.score
+
+- else
+  p = t('.no_data_available')
diff --git a/app/views/exercises/statistics.html.slim b/app/views/exercises/statistics.html.slim
index 77ab091d..0cb26e9a 100644
--- a/app/views/exercises/statistics.html.slim
+++ b/app/views/exercises/statistics.html.slim
@@ -7,3 +7,23 @@ h1 = @exercise
 = row(label: '.average_score') do
   p == @exercise.average_score ? t('shared.out_of', maximum_value: @exercise.maximum_score, value: @exercise.average_score.round(2)) : empty
   p = progress_bar(@exercise.average_percentage)
+
+= row(label: '.average_worktime') do
+  p = @exercise.average_working_time
+
+- Hash[:internal_users => t('.internal_users'), :external_users => t('.external_users')].each_pair do |symbol, label|
+  strong = label
+  .table-responsive
+    table.table
+      thead
+        tr
+          - ['.user', '.score', '.runs', '.worktime'].each do |title|
+            th.header = t(title)
+      tbody
+        - @exercise.send(symbol).distinct().each do |user|
+          tr
+            - submissions = @exercise.submissions.where('user_id=?', user.id)
+            td = link_to_if symbol==:external_users, "#{user.name} (#{user.email})", {controller: "exercises", action: "statistics", external_user_id: user.id, id: @exercise.id}
+            td = submissions.maximum('score') or 0
+            td = submissions.count('id')
+            td = @exercise.average_working_time_for(user.id) or 0
diff --git a/app/views/external_users/statistics.html.slim b/app/views/external_users/statistics.html.slim
new file mode 100644
index 00000000..6c49b967
--- /dev/null
+++ b/app/views/external_users/statistics.html.slim
@@ -0,0 +1,2 @@
+h1 = @user
+H2 = 'Hallo'
\ No newline at end of file
diff --git a/config/locales/de.yml b/config/locales/de.yml
index 647fbaee..d96e6927 100644
--- a/config/locales/de.yml
+++ b/config/locales/de.yml
@@ -167,6 +167,11 @@ de:
     shell:
       command: Befehl
       headline: Shell
+    statistics:
+      exercise: Übung
+      score: Durchschnittliche Punktzahl
+      runs: Durchschnittliche Anzahl von Versuchen
+      worktime: Durchschnittliche Arbeitszeit
   exercises:
     editor:
       confirm_start_over: Wollen Sie wirklich von vorne anfangen?
@@ -239,8 +244,21 @@ de:
       intermediate_submissions: Intermediäre Abgaben
       participants: Bearbeitende Nutzer
       users: '%{count} verschiedene Nutzer'
+      user: Nutzer
+      score: Punktzahl
+      runs: Versuche
+      worktime: Arbeitszeit
+      average_worktime: Durchschnittliche Arbeitszeit
+      internal_users: Interne Nutzer
+      external_user: Externe Nutzer
     submit:
       failure: Beim Übermitteln Ihrer Punktzahl ist ein Fehler aufgetreten. Bitte versuchen Sie es später erneut.
+    external_users:
+      statistics:
+        no_data_available: Keine Daten verfügbar.
+        time: Zeit
+        cause: Grund
+        score: Punktzahl
   files:
     roles:
       main_file: Hauptdatei
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 3af56f90..dc63e3dd 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -167,6 +167,11 @@ en:
     shell:
       command: Command
       headline: Shell
+    statistics:
+      exercise: Exercise
+      score: Average Score
+      runs: Average Number of Runs
+      worktime: Average Working Time
   exercises:
     editor:
       confirm_start_over: Do you really want to start over?
@@ -239,8 +244,21 @@ en:
       intermediate_submissions: Intermediate Submissions
       participants: Participating Users
       users: '%{count} distinct users'
+      user: User
+      score: Score
+      runs: Runs
+      worktime: Working Time
+      average_worktime: Average Working Time
+      internal_users: Internal Users
+      external_users: External Users
     submit:
       failure: An error occured while transmitting your score. Please try again later.
+    external_users:
+      statistics:
+        no_data_available: No data available.
+        time: Time
+        cause: Cause
+        score: Score
   files:
     roles:
       main_file: Main File
diff --git a/config/routes.rb b/config/routes.rb
index 1616d9b8..24f6a0d9 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -20,12 +20,20 @@ Rails.application.routes.draw do
 
   get '/help', to: 'application#help'
 
+  concern :statistics do
+    member do
+      get :statistics
+    end
+  end
+
+
   resources :consumers
 
   resources :execution_environments do
     member do
       get :shell
       post 'shell', as: :execute_command, to: :execute_command
+      get :statistics
     end
 
     resources :errors, only: [:create, :index, :show]
@@ -46,7 +54,9 @@ Rails.application.routes.draw do
     end
   end
 
-  resources :external_users, only: [:index, :show]
+  resources :external_users, only: [:index, :show], concerns: :statistics do
+    resources :exercises, concerns: :statistics
+  end
 
   namespace :code_ocean do
     resources :files, only: [:create, :destroy]
diff --git a/spec/controllers/execution_environments_controller_spec.rb b/spec/controllers/execution_environments_controller_spec.rb
index 331c3ec7..2abf59ef 100644
--- a/spec/controllers/execution_environments_controller_spec.rb
+++ b/spec/controllers/execution_environments_controller_spec.rb
@@ -130,6 +130,14 @@ describe ExecutionEnvironmentsController do
     expect_template(:shell)
   end
 
+  describe 'GET #statistics' do
+    before(:each) { get :statistics, id: execution_environment.id }
+
+    expect_assigns(execution_environment: :execution_environment)
+    expect_status(200)
+    expect_template(:statistics)
+  end
+
   describe 'GET #show' do
     before(:each) { get :show, id: execution_environment.id }