diff --git a/src/app.py b/src/app.py
index 4ebb1d9..a8e7bbd 100644
--- a/src/app.py
+++ b/src/app.py
@@ -56,11 +56,15 @@ def get_activities():
 def signup_for_activity(activity_name: str, email: str):
     """Sign up a student for an activity"""
     # Validate activity exists
+    
     if activity_name not in activities:
         raise HTTPException(status_code=404, detail="Activity not found")
 
     # Get the specific activity
     activity = activities[activity_name]
+    # Validate student is not already signed up
+    if email in activity["participants"]:
+        raise HTTPException(status_code=400, detail="Student is already signed up")
 
     # Add student
     activity["participants"].append(email)
diff --git a/{file_path} b/{file_path}
new file mode 100644
index 0000000..02eddd5
--- /dev/null
+++ b/{file_path}
@@ -0,0 +1,6 @@
+Sports: rock climbing
+Sports: badminton
+Artistic: pottery
+Artistic: digital illustration
+Intellectual: chess puzzles
+Intellectual: philosophy reading