diff --git a/app/models/exercise.rb b/app/models/exercise.rb
index 37e421a7..0f691fde 100644
--- a/app/models/exercise.rb
+++ b/app/models/exercise.rb
@@ -107,7 +107,7 @@ class Exercise < ActiveRecord::Base
                     (created_at - lag(created_at) over (PARTITION BY user_id
                                                         ORDER BY created_at)) AS working_time
             FROM submissions
-            WHERE exercise_id=#{id} and user_id=#{user_id}) AS foo) AS bar
+            WHERE exercise_id=#{id} and user_id=#{user_id} and user_type='ExternalUser') AS foo) AS bar
     """).first["working_time"]
   end
 
@@ -172,8 +172,12 @@ class Exercise < ActiveRecord::Base
   end
   private :generate_token
 
-  def maximum_score
-    files.teacher_defined_tests.sum(:weight)
+  def maximum_score(*user)
+    if user
+      submissions.where(user: user, cause: "assess").where("score IS NOT NULL").order("score DESC").first.score || 0 rescue 0
+    else
+      files.teacher_defined_tests.sum(:weight)
+    end
   end
 
   def set_default_values
diff --git a/app/models/proxy_exercise.rb b/app/models/proxy_exercise.rb
index 2bf3658b..2efa8962 100644
--- a/app/models/proxy_exercise.rb
+++ b/app/models/proxy_exercise.rb
@@ -43,8 +43,22 @@ class ProxyExercise < ActiveRecord::Base
       exercises.shuffle.first
     end
 
+    # [score][quantile]
+    def scoring_matrix
+      [
+          [0  ,0  ,0  ,0  ,0  ],
+          [0.2,0.2,0.2,0.2,0.1],
+          [0.5,0.5,0.4,0.4,0.3],
+          [0.6,0.6,0.5,0.5,0.4],
+          [1  ,1  ,0.9,0.8,0.7],
+      ]
+    end
+
     def score(user, ex)
-      1
+      points_ratio =  ex.maximum_score(user) / ex.maximum_score.to_f
+      working_time_user = Time.parse(ex.average_working_time_for_only(user.id) || "00:00:00")
+      scoring_matrix = scoring_matrix
+
     end
 
     def getRelativeKnowledgeLoss(user, execises)