diff --git a/syncortexGA/models/timetable_model.py b/syncortexGA/models/timetable_model.py
index aa5b391..c8db99e 100644
--- a/syncortexGA/models/timetable_model.py
+++ b/syncortexGA/models/timetable_model.py
@@ -77,7 +77,6 @@ class Course(BaseModel):
     has_lab: bool = False
     lab_slot: Optional[TimeSlot] = None
     lab_room_id: Optional[int] = None
-    lab_instructor_id: Optional[int] = None
     session_pattern: Optional[SessionPattern] = None
 
     @model_validator(mode="after")
@@ -95,6 +94,23 @@ def validate_course(cls, model):
         return model
 
 
+class CourseOffering(BaseModel):
+    """
+    Represents the offering of a course by an instructor for a specific subgroup.
+    Allows multiple instructors to offer the same course to different subgroups,
+    and a single instructor to teach the same course in multiple subgroups.
+
+    Attributes:
+        course_id (int): Identifier of the course being offered.
+        instructor_id (int): Identifier of the instructor teaching the course.
+        sub_group (int): Sub-group number within the course offering. Default is 1.
+    """
+
+    course_id: int
+    instructor_id: int
+    sub_group: int = 1  # Default subgroup is 1
+
+
 # ========== Student ==========
 class Student(BaseModel):
     """Represents a student belonging to a specific group."""
diff --git a/tests/unit/test_models.py b/tests/unit/test_models.py
index a3f577a..f2d2a9c 100644
--- a/tests/unit/test_models.py
+++ b/tests/unit/test_models.py
@@ -6,6 +6,7 @@
     AlternatingSessionPattern,
     SessionPattern,
     Course,
+    CourseOffering,
     Student,
     StudentGroup,
     Instructor,
@@ -329,3 +330,33 @@ def test_timetable_valid():
 def test_timetable_empty():
     timetable = Timetable(sessions=[])
     assert timetable.sessions == []
+
+
+def test_course_offering_valid_defaults():
+    offering = CourseOffering(course_id=10, instructor_id=5)
+    assert offering.course_id == 10
+    assert offering.instructor_id == 5
+    assert offering.sub_group == 1  # Default value
+
+
+def test_course_offering_valid_with_subgroup():
+    offering = CourseOffering(course_id=20, instructor_id=7, sub_group=3)
+    assert offering.course_id == 20
+    assert offering.instructor_id == 7
+    assert offering.sub_group == 3
+
+
+def test_course_offering_invalid_missing_course_id():
+    with pytest.raises(ValidationError):
+        CourseOffering(instructor_id=1)
+
+
+def test_course_offering_invalid_missing_instructor_id():
+    with pytest.raises(ValidationError):
+        CourseOffering(course_id=1)
+
+
+def test_course_offering_invalid_sub_group_type():
+    # sub_group should be int
+    with pytest.raises(ValidationError):
+        CourseOffering(course_id=1, instructor_id=1, sub_group="two")