diff --git a/knowledge.py b/knowledge.py
index 981a72f..2377576 100644
--- a/knowledge.py
+++ b/knowledge.py
@@ -144,13 +144,13 @@ class StudentKnowledge(object):
     #   - if answer ok, goes to next question
     #   - if wrong, counts number of tries. If exceeded, moves on.
     # ------------------------------------------------------------------------
-    def check_answer(self, answer):
+    async def check_answer(self, answer):
         logger.debug('StudentKnowledge.check_answer()')
 
         q = self.current_question
         q['answer'] = answer
         q['finish_time'] = datetime.now()
-        grade = q.correct()
+        grade = await q.correct_async()
 
         logger.debug(f'Grade {grade:.2} ({q["ref"]})')
 
diff --git a/learnapp.py b/learnapp.py
index 87fb66a..9013e15 100644
--- a/learnapp.py
+++ b/learnapp.py
@@ -138,14 +138,14 @@ class LearnApp(object):
     # ------------------------------------------------------------------------
     # checks answer (updating student state) and returns grade.
     # ------------------------------------------------------------------------
-    def check_answer(self, uid, answer):
+    async def check_answer(self, uid, answer):
         knowledge = self.online[uid]['state']
-        q = knowledge.check_answer(answer) # also moves to next question
+        q = await knowledge.check_answer(answer) # also moves to next question
         logger.info(f'User "{uid}" got {q["grade"]:.2} in question "{q["ref"]}"')
         topic = knowledge.get_current_topic()
 
         # always save grade of answered question
-        with self.db_session(autoflush=False) as s:
+        with self.db_session() as s:
             s.add(Answer(
                 ref=q['ref'],
                 grade=q['grade'],
@@ -155,13 +155,13 @@ class LearnApp(object):
                 topic_id=topic))
             logger.debug(f'Saved "{q["ref"]}" into database')
 
-            if knowledge.get_current_question() is None:
-                # finished topic, save into database
-                logger.info(f'User "{uid}" finished "{topic}"')
-                level = knowledge.get_topic_level(topic)
-                date = str(knowledge.get_topic_date(topic))
+        if knowledge.get_current_question() is None:
+            # finished topic, save into database
+            logger.info(f'User "{uid}" finished "{topic}"')
+            level = knowledge.get_topic_level(topic)
+            date = str(knowledge.get_topic_date(topic))
 
-                # with self.db_session(autoflush=False) as s:
+            with self.db_session() as s:
                 a = s.query(StudentTopic).filter_by(student_id=uid, topic_id=topic).one_or_none()
                 if a is None:
                     # insert new studenttopic into database
@@ -175,11 +175,10 @@ class LearnApp(object):
                     a.date = date
 
                 s.add(a)
-                logger.debug(f'Saved topic "{topic}" into database')
 
-
-        if knowledge.get_current_question() is None:
+            logger.debug(f'Saved topic "{topic}" into database')
             return 'finished_topic'
+
         if q['tries'] > 0 and q['grade'] <= 0.999:
             return 'wrong'
         # elif q['tries'] <= 0 and q['grade'] <= 0.999:
diff --git a/serve.py b/serve.py
index a23d599..073e3e8 100755
--- a/serve.py
+++ b/serve.py
@@ -275,8 +275,10 @@ class QuestionHandler(BaseHandler):
             answer = answer[0]
 
         # check answer in another thread (nonblocking)
-        action = await asyncio.get_event_loop().run_in_executor(None,
-            self.learn.check_answer, user, answer)
+        # action = await asyncio.get_event_loop().run_in_executor(None,
+        #     self.learn.check_answer, user, answer)
+        action = await self.learn.check_answer(user, answer)
+
 
         # get next question (same, new or None)
         question = self.learn.get_current_question(user)
--
libgit2 0.21.2