diff --git a/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/CalendarEvent.kt b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/CalendarEvent.kt
new file mode 100644
index 00000000..17731f40
--- /dev/null
+++ b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/CalendarEvent.kt
@@ -0,0 +1,14 @@
+package com.intelligentbackpack.schooldomain.entities.calendar
+
+import java.time.LocalTime
+
+/**
+ * An event in the calendar.
+ *
+ * @property startTime the time the event starts
+ * @property endTime the time the event ends
+ */
+interface CalendarEvent {
+    val startTime: LocalTime
+    val endTime: LocalTime
+}
diff --git a/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/DateEvent.kt b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/DateEvent.kt
new file mode 100644
index 00000000..f0ca87e5
--- /dev/null
+++ b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/DateEvent.kt
@@ -0,0 +1,12 @@
+package com.intelligentbackpack.schooldomain.entities.calendar
+
+import java.time.LocalDate
+
+/**
+ * An event that happens on a specific date.
+ *
+ * @property date the date of the event
+ */
+interface DateEvent : CalendarEvent {
+    val date: LocalDate
+}
diff --git a/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/DateLesson.kt b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/DateLesson.kt
new file mode 100644
index 00000000..3c4ba1a5
--- /dev/null
+++ b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/DateLesson.kt
@@ -0,0 +1,8 @@
+package com.intelligentbackpack.schooldomain.entities.calendar
+
+/**
+ * Represents a lesson that occurs on a specific date.
+ *
+ * @property date the date of the lesson
+ */
+interface DateLesson : Lesson, DateEvent
diff --git a/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/Lesson.kt b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/Lesson.kt
new file mode 100644
index 00000000..5300b9a6
--- /dev/null
+++ b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/Lesson.kt
@@ -0,0 +1,20 @@
+package com.intelligentbackpack.schooldomain.entities.calendar
+
+import com.intelligentbackpack.schooldomain.entities.Class
+import com.intelligentbackpack.schooldomain.entities.Subject
+import com.intelligentbackpack.schooldomain.entities.person.Professor
+
+/**
+ * A lesson.
+ *
+ * @property subject the subject of the lesson
+ * @property module the module of the lesson
+ * @property professor the professor of the lesson
+ * @property studentsClass the class of the lesson
+ */
+interface Lesson : CalendarEvent {
+    val subject: Subject
+    val module: String?
+    val professor: Professor
+    val studentsClass: Class
+}
diff --git a/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/WeekEvent.kt b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/WeekEvent.kt
new file mode 100644
index 00000000..84a33c1d
--- /dev/null
+++ b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/WeekEvent.kt
@@ -0,0 +1,17 @@
+package com.intelligentbackpack.schooldomain.entities.calendar
+
+import java.time.DayOfWeek
+import java.time.LocalDate
+
+/**
+ * An event that happens every week at the same time on the same day of the week for a certain period of time.
+ *
+ * @property day the day of the week the event happens
+ * @property fromDate the date from which the event happens
+ * @property toDate the date until which the event happens
+ */
+interface WeekEvent : CalendarEvent {
+    val day: DayOfWeek
+    val fromDate: LocalDate
+    val toDate: LocalDate
+}
diff --git a/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/WeekLesson.kt b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/WeekLesson.kt
new file mode 100644
index 00000000..0a9bd596
--- /dev/null
+++ b/schoolDomain/src/main/kotlin/com/intelligentbackpack/schooldomain/entities/calendar/WeekLesson.kt
@@ -0,0 +1,6 @@
+package com.intelligentbackpack.schooldomain.entities.calendar
+
+/**
+ * A lesson that happens every week at the same time on the same day.
+ */
+interface WeekLesson : Lesson, WeekEvent