diff --git a/biscuit/apps/chronos/model_extensions.py b/biscuit/apps/chronos/model_extensions.py
index 25acbd54c8906fcf461662d7c5344082b9f96a8e..b4a6d4adab7ae78f62e8cbca2d0e7ee5a2da13bf 100644
--- a/biscuit/apps/chronos/model_extensions.py
+++ b/biscuit/apps/chronos/model_extensions.py
@@ -1,8 +1,18 @@
 from biscuit.core.models import Person
 
-from .models import Lesson
+from .models import Lesson, LessonPeriod
 
 
 @Person.property
 def lessons_as_participant(self):
     return Lesson.objects.filter(groups__members=self)
+
+
+@Person.property
+def lesson_periods_as_participant(self):
+    return LessonPeriod.objects.filter(lesson__groups__members=self)
+
+
+@Person.property
+def lesson_periods_as_teacher(self):
+    return LessonPeriod.objects.filter(lesson__teachers=self)