diff --git a/aleksis/apps/lesrooster/admin.py b/aleksis/apps/lesrooster/admin.py
index 7277556372c304a5512a0fae39b85a52fad113c7..c04107549275dce4f357c068466b8ad38f3189e3 100644
--- a/aleksis/apps/lesrooster/admin.py
+++ b/aleksis/apps/lesrooster/admin.py
@@ -17,7 +17,7 @@ admin.site.register(ValidityRange, ValidityRangeAdmin)
 
 
 class SlotAdmin(admin.ModelAdmin):
-    list_display = ("school_term", "weekday", "period", "time_start", "time_end")
+    list_display = ("validity_range", "weekday", "period", "time_start", "time_end")
     list_display_links = ("weekday", "period")
 
 
diff --git a/aleksis/apps/lesrooster/models.py b/aleksis/apps/lesrooster/models.py
index 2fcfc4e488610dbc5b8f184a47e93636e5a441af..dd6800cad5176070d0bf5ccde187587f6b917f51 100644
--- a/aleksis/apps/lesrooster/models.py
+++ b/aleksis/apps/lesrooster/models.py
@@ -90,7 +90,7 @@ class Slot(ExtensiblePolymorphicModel):
     WEEKDAY_CHOICES_SHORT = i18n_day_abbr_choices_lazy()
 
     validity_range = models.ForeignKey(
-        "chronos.ValidityRange",
+        "lesrooster.ValidityRange",
         on_delete=models.CASCADE,
         related_name="slots",
         verbose_name=_("Linked validity range"),
@@ -133,11 +133,16 @@ class Slot(ExtensiblePolymorphicModel):
             day = self.get_date(date_ref)
         return datetime.combine(day, self.time_end)
 
+    @property
+    def lessons(self):
+        # FIXME: this may not be the intended behaviour of this property
+        return Lesson.objects.filter(models.Q(lesson_start=self) | models.Q(lesson_end=self))
+
     class Meta:
         constraints = [
             # Heads up: Uniqueness per validity range implies validity per site
             models.UniqueConstraint(
-                fields=["weekday", "period", "validity"], name="unique_period_per_range"
+                fields=["weekday", "period", "validity_range"], name="unique_period_per_range"
             ),
         ]
         ordering = ["weekday", "period"]
@@ -161,13 +166,13 @@ class Lesson(ExtensibleModel):
         Slot,
         on_delete=models.CASCADE,
         verbose_name=_("Start slot"),
-        related_name="lessons",
+        related_name="lessons_starting",
     )
     slot_end = models.ForeignKey(
         Slot,
         on_delete=models.CASCADE,
         verbose_name=_("End slot"),
-        related_name="lessons",
+        related_name="lessons_ending",
     )
 
     # Recurrence rules allow to define a series of lessons
@@ -212,7 +217,7 @@ class Lesson(ExtensibleModel):
     class Meta:
         # Heads up: Link to slot implies uniqueness per site
         ordering = [
-            "slot_start__validity__date_start",
+            "slot_start__validity_range__date_start",
             "slot_start__weekday",
             "slot_start__time_start",
             "subject",