diff --git a/knowledge.py b/knowledge.py
index c91f2c1..9ef0b64 100644
--- a/knowledge.py
+++ b/knowledge.py
@@ -94,6 +94,11 @@ class StudentKnowledge(object):
         self.correct_answers = 0
         self.wrong_answers = 0
         self.finished_questions = []
+
+
+        # TODO select a subset of question and randomize order
+        questionlist = random.sample(questionlist, k=min(8, len(questionlist)))
+
         self.questions = [factory[qref].generate() for qref in questionlist]
         logger.debug(f'Total: {len(self.questions)} questions')
 
@@ -137,10 +142,11 @@ class StudentKnowledge(object):
         grade = q.correct()
         logger.debug(f'Grade = {grade:.2} ({q["ref"]})')
 
+        self.finished_questions.append(q)  # both correct and wrong answers 
+
         # if answer is correct, get next question
         if grade > 0.999:
             self.correct_answers += 1
-            self.finished_questions.append(q)
             try:
                 self.current_question = self.questions.pop(0) # FIXME empty?
             except IndexError:
diff --git a/serve.py b/serve.py
index 26fd166..61411bc 100755
--- a/serve.py
+++ b/serve.py
@@ -256,15 +256,15 @@ class QuestionHandler(BaseHandler):
 
         # check answer and get next question (same, new or None)
         answer = self.get_body_arguments('answer')  # list
-        if not answer:
+
+        # answers returned in a list. fix depending on question type
+        qtype = self.learn.get_student_question_type(user)
+        if qtype in ('success', 'information', 'info'):  # FIXME unused?
             answer = None
-        else:
-            # answers returned in a list. fix depending on question type
-            qtype = self.learn.get_student_question_type(user)
-            if qtype in ('success', 'information', 'info'):  # FIXME unused?
-                answer = None
-            elif qtype != 'checkbox':   # radio, text, textarea, ...
-                answer = answer[0]
+        elif qtype == 'radio' and not answer:
+            answer = None
+        elif qtype != 'checkbox':   # radio, text, textarea, ...
+            answer = answer[0]
 
         # check answer in another thread (nonblocking)
         loop = asyncio.get_event_loop()
--
libgit2 0.21.2