diff --git a/src/app.py b/src/app.py
index 4ebb1d9..c5e605e 100644
--- a/src/app.py
+++ b/src/app.py
@@ -38,6 +38,45 @@
         "schedule": "Mondays, Wednesdays, Fridays, 2:00 PM - 3:00 PM",
         "max_participants": 30,
         "participants": ["john@mergington.edu", "olivia@mergington.edu"]
+    },
+    # Sports related activities
+    "Soccer Team": {
+        "description": "Join the school soccer team and compete in local leagues",
+        "schedule": "Tuesdays and Thursdays, 4:00 PM - 5:30 PM",
+        "max_participants": 18,
+        "participants": ["lucas@mergington.edu", "mia@mergington.edu"]
+    },
+    "Basketball Club": {
+        "description": "Practice basketball skills and play friendly matches",
+        "schedule": "Wednesdays, 3:30 PM - 5:00 PM",
+        "max_participants": 15,
+        "participants": ["liam@mergington.edu", "ava@mergington.edu"]
+    },
+    # Artistic activities
+    "Art Club": {
+        "description": "Explore painting, drawing, and other visual arts",
+        "schedule": "Mondays, 3:30 PM - 5:00 PM",
+        "max_participants": 16,
+        "participants": ["ella@mergington.edu", "noah@mergington.edu"]
+    },
+    "Drama Society": {
+        "description": "Participate in theater productions and acting workshops",
+        "schedule": "Fridays, 4:00 PM - 6:00 PM",
+        "max_participants": 20,
+        "participants": ["amelia@mergington.edu", "jack@mergington.edu"]
+    },
+    # Intellectual activities
+    "Math Olympiad": {
+        "description": "Prepare for math competitions and solve challenging problems",
+        "schedule": "Thursdays, 3:30 PM - 5:00 PM",
+        "max_participants": 10,
+        "participants": ["ethan@mergington.edu", "grace@mergington.edu"]
+    },
+    "Science Club": {
+        "description": "Conduct experiments and explore scientific concepts",
+        "schedule": "Wednesdays, 4:00 PM - 5:30 PM",
+        "max_participants": 14,
+        "participants": ["benjamin@mergington.edu", "chloe@mergington.edu"]
     }
 }
 
@@ -62,6 +101,10 @@ def signup_for_activity(activity_name: str, email: str):
     # 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 already signed up")
+
     # Add student
     activity["participants"].append(email)
     return {"message": f"Signed up {email} for {activity_name}"}
diff --git a/src/static/app.js b/src/static/app.js
index dcc1e38..01df780 100644
--- a/src/static/app.js
+++ b/src/static/app.js
@@ -25,6 +25,12 @@ document.addEventListener("DOMContentLoaded", () => {
           <p>${details.description}</p>
           <p><strong>Schedule:</strong> ${details.schedule}</p>
           <p><strong>Availability:</strong> ${spotsLeft} spots left</p>
+          <div class="participants-section">
+            <strong>Participants:</strong>
+            <ul class="participants-list">
+              ${details.participants.length > 0 ? details.participants.map(p => `<li>${p}</li>`).join("") : '<li><em>No participants yet</em></li>'}
+            </ul>
+          </div>
         `;
 
         activitiesList.appendChild(activityCard);
diff --git a/src/static/styles.css b/src/static/styles.css
index a533b32..adfd8cf 100644
--- a/src/static/styles.css
+++ b/src/static/styles.css
@@ -142,3 +142,26 @@ footer {
   padding: 20px;
   color: #666;
 }
+
+.participants-section {
+  margin-top: 10px;
+  padding: 10px;
+  background-color: #eef3fb;
+  border-radius: 4px;
+}
+
+.participants-section strong {
+  color: #1a237e;
+}
+
+.participants-list {
+  margin: 8px 0 0 18px;
+  padding: 0;
+  list-style-type: disc;
+  color: #333;
+  font-size: 15px;
+}
+
+.participants-list li {
+  margin-bottom: 3px;
+}