diff --git a/advlabdb/assistantModelViews.py b/advlabdb/assistantModelViews.py
index fe1bbe5..e49a0f2 100644
--- a/advlabdb/assistantModelViews.py
+++ b/advlabdb/assistantModelViews.py
@@ -11,6 +11,8 @@ from advlabdb import assistantSpace, db
 from advlabdb.customClasses import SecureAssistantBaseView, SecureAssistantModelView
 from advlabdb.exceptions import DataBaseException, ModelViewException
 from advlabdb.models import (
+    MAX_MARK,
+    MIN_MARK,
     Appointment,
     Assistant,
     Experiment,
@@ -91,8 +93,8 @@ class AssistantExperimentMarkView(SecureAssistantModelView):
         "part_student.part": "Part",
     }
     column_descriptions = {
-        "oral_mark": "Between 0 and 15",
-        "protocol_mark": "Between 0 and 15",
+        "oral_mark": f"Between {MIN_MARK} and {MAX_MARK}",
+        "protocol_mark": f"Between {MIN_MARK} and {MAX_MARK}",
         "final_experiment_mark": "Calculated automatically with oral and protocol marks and weightings",
         "part_student.student.contact_email": "The preferred contact email address if entered by the student",
         "assistant": "The last assistant who edited the mark",
@@ -106,8 +108,8 @@ class AssistantExperimentMarkView(SecureAssistantModelView):
     form_columns = column_editable_list
 
     form_args = {
-        "oral_mark": {"validators": [NumberRange(0, 15)]},
-        "protocol_mark": {"validators": [NumberRange(0, 15)]},
+        "oral_mark": {"validators": [NumberRange(MIN_MARK, MAX_MARK)]},
+        "protocol_mark": {"validators": [NumberRange(MIN_MARK, MAX_MARK)]},
     }
 
     column_default_sort = [("oral_mark", False), ("protocol_mark", False)]
diff --git a/advlabdb/models.py b/advlabdb/models.py
index 1697f9a..fb332e7 100644
--- a/advlabdb/models.py
+++ b/advlabdb/models.py
@@ -16,6 +16,9 @@ from advlabdb import db
 from advlabdb.configUtils import getConfig
 from advlabdb.exceptions import DataBaseException
 
+MIN_MARK = 0
+MAX_MARK = 15
+
 
 def roundHalfUpToInt(number):
     return int(Decimal(number).quantize(Decimal(0), rounding=ROUND_HALF_UP))
@@ -46,8 +49,8 @@ class PartStudent(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     final_part_mark = db.Column(
         db.Integer,
-        db.CheckConstraint("final_part_mark > -1"),
-        db.CheckConstraint("final_part_mark < 16"),
+        db.CheckConstraint(f"final_part_mark >= {MIN_MARK}"),
+        db.CheckConstraint(f"final_part_mark <= {MAX_MARK}"),
         nullable=True,
     )
 
@@ -497,21 +500,21 @@ class ExperimentMark(db.Model):
 
     oral_mark = db.Column(
         db.Integer,
-        db.CheckConstraint("oral_mark > -1"),
-        db.CheckConstraint("oral_mark < 16"),
+        db.CheckConstraint(f"oral_mark >= {MIN_MARK}"),
+        db.CheckConstraint(f"oral_mark <= {MIN_MARK}"),
         nullable=True,
     )
     protocol_mark = db.Column(
         db.Integer,
-        db.CheckConstraint("protocol_mark > -1"),
-        db.CheckConstraint("protocol_mark < 16"),
+        db.CheckConstraint(f"oral_mark >= {MIN_MARK}"),
+        db.CheckConstraint(f"oral_mark <= {MIN_MARK}"),
         nullable=True,
     )
 
     final_experiment_mark = db.Column(
         db.Integer,
-        db.CheckConstraint("protocol_mark > -1"),
-        db.CheckConstraint("protocol_mark < 16"),
+        db.CheckConstraint(f"oral_mark >= {MIN_MARK}"),
+        db.CheckConstraint(f"oral_mark <= {MIN_MARK}"),
         onupdate=final_experiment_mark_update,
         nullable=True,
     )