diff --git a/biscuit/apps/chronos/model_extensions.py b/biscuit/apps/chronos/model_extensions.py
new file mode 100644
index 0000000000000000000000000000000000000000..35afb5c3ee89649d941f8a7a8fa96ac7b2c8ba66
--- /dev/null
+++ b/biscuit/apps/chronos/model_extensions.py
@@ -0,0 +1,8 @@
+from biscuit.core.models import Person
+
+from .models import Lesson
+
+
+@Person.property
+def lessons_as_participant(self):
+    return Lesson.objects.filter(groups__member=self)