diff --git a/access/serializers.py b/access/serializers.py
index 425ffd5..e59a1c1 100644
--- a/access/serializers.py
+++ b/access/serializers.py
@@ -79,7 +79,8 @@ class UserSearchSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = get_user_model()
-        fields = ('photo', 'out_key', 'email', 'first_name', 'last_name', 'phone', 'pay', 'last_request')
+        fields = ('photo', 'out_key', 'email', 'first_name',
+                  'last_name', 'phone', 'pay', 'last_request')
 
     @staticmethod
     def get_phone(self):
@@ -91,7 +92,11 @@ class UserSearchSerializer(serializers.ModelSerializer):
 
     @staticmethod
     def get_photo(self):
-        return self.account.photo.url
+        try:
+            url = self.account.photo.url
+        except ValueError:
+            url = None
+        return url
 
     @staticmethod
     def get_last_request(self):
diff --git a/courses/api.py b/courses/api.py
index af81ce0..2b4e99a 100644
--- a/courses/api.py
+++ b/courses/api.py
@@ -14,7 +14,6 @@ class InApiTeacher:
         course = Course.objects.get(slug=slug)
         course.teacher_tokens.remove(token)
         course.save()
-        return None
 
     @staticmethod
     def get_token_list(slug: str) -> list:
@@ -26,4 +25,21 @@ class CourseProgressApi:
     @staticmethod
     def get_topic_lesson(course_token: str):
         course = Course.objects.get(token=course_token)
-        return [[lesson.token for lesson in topic.lesson_set.all()] for topic in course.topic_set.all()]
\ No newline at end of file
+        return [[lesson.token for lesson in topic.lesson_set.all()] for topic in course.topic_set.all()]
+
+    @staticmethod
+    def get_next(course_token: str, lesson_list: list):
+        """
+
+        :param course_token:
+        :param lesson_list:
+        :return: следующий урок для прохождения и требует ли он валидации
+        """
+        course = Course.objects.get(token=course_token)
+        acc = None
+        for lesson in course.get_lesson_list():
+            if not lesson.token in lesson_list:
+                acc = (lesson.token, lesson.is_hm)
+                break
+
+        return acc
\ No newline at end of file
diff --git a/courses/models.py b/courses/models.py
index 700c853..c090554 100755
--- a/courses/models.py
+++ b/courses/models.py
@@ -91,6 +91,12 @@ class Course(models.Model):
             'task_count': sum([topic.lesson_set.count() for topic in self.topic_set.all()])
         }
 
+    def get_lesson_list(self) -> list:
+        lesson_list = []
+        for topic in self.topic_set.all():
+            lesson_list += list(topic.lesson_set.all())
+        return lesson_list
+
     objects = CourseManager()
 
     class Meta:
diff --git a/progress/serializers.py b/progress/serializers.py
index 09d4abd..00a32a9 100644
--- a/progress/serializers.py
+++ b/progress/serializers.py
@@ -41,4 +41,4 @@ class ProgressLessonSerializer(serializers.ModelSerializer):
 
     @staticmethod
     def get_teacher(self):
-        return self.teacher.get_full_name()
\ No newline at end of file
+        return self.checker.get_full_name()
\ No newline at end of file