diff --git a/BUGS.md b/BUGS.md
index 05fb929..9959fe2 100644
--- a/BUGS.md
+++ b/BUGS.md
@@ -1,6 +1,7 @@
 
 BUGS:
 
+- level depender do numero de respostas correctas
 - pymips: activar/desactivar instruções
 - tabs em textarea nao funcionam correctamente (insere 1 espaco em vez de 4)
 - reportar comentarios após submeter.
diff --git a/knowledge.py b/knowledge.py
index 81d8e9c..6450e12 100644
--- a/knowledge.py
+++ b/knowledge.py
@@ -32,7 +32,7 @@ class Knowledge(object):
         if topic is None:
             # select the first topic that has level < 0.9
             for topic in self.topic_sequence:
-                if topic not in self.state or self.state[topic]['level'] < 0.9:
+                if topic not in self.state or self.state[topic]['level'] < 0.8:
                     break
         logger.debug(f'Student {self.student}: new_topic({topic})')
 
@@ -42,6 +42,8 @@ class Knowledge(object):
         self.questions = self.generate_questions_for_topic(topic)
         self.current_question = None
         self.finished_questions = []
+        self.correct_answers = 1
+        self.wrong_answers = 0
 
     # ------------------------------------------------------------------------
     def generate_questions_for_topic(self, topic):
@@ -85,7 +87,7 @@ class Knowledge(object):
             # keep going if there are no questions in the next topics
             while not self.questions:
                 self.state[self.current_topic] = {
-                    'level': 1.0, # FIXME depends on how many are correct
+                    'level': self.correct_answers / (self.correct_answers + self.wrong_answers),
                     'date': datetime.now()
                 }
                 self.new_topic()
@@ -103,8 +105,12 @@ class Knowledge(object):
         question = self.current_question
         if question is not None:
             question['finish_time'] = datetime.now()
-            question.correct(answer)
+            grade = question.correct(answer)
+            if grade > 0.9:
+                self.correct_answers += 1
+            else:
+                self.wrong_answers +=1
 
-            logger.debug(f'Student {self.student}: check_answer({answer}) = {question["grade"]}')
+            logger.debug(f'Student {self.student}: check_answer({answer}) = {grade}')
 
         return question
--
libgit2 0.21.2