diff --git a/src/app.py b/src/app.py
index 4ebb1d9..f1f607b 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": ["noah@mergington.edu", "isabella@mergington.edu"]
+    },
+    "Drama Society": {
+        "description": "Participate in school plays and drama workshops",
+        "schedule": "Fridays, 4:00 PM - 5:30 PM",
+        "max_participants": 20,
+        "participants": ["charlotte@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": ["amelia@mergington.edu", "benjamin@mergington.edu"]
+    },
+    "Science Club": {
+        "description": "Conduct experiments and explore scientific concepts",
+        "schedule": "Wednesdays, 4:00 PM - 5:00 PM",
+        "max_participants": 14,
+        "participants": ["elijah@mergington.edu", "harper@mergington.edu"]
     }
 }
 
@@ -55,6 +94,11 @@ def get_activities():
 @app.post("/activities/{activity_name}/signup")
 def signup_for_activity(activity_name: str, email: str):
     """Sign up a student for an activity"""
+    # Validate student is not already signed up
+    for activity in activities.values():
+        if email in activity["participants"]:
+            raise HTTPException(status_code=400, detail="Student already signed up for an activity")
+        
     # Validate activity exists
     if activity_name not in activities:
         raise HTTPException(status_code=404, detail="Activity not found")
diff --git a/src/static/app.js b/src/static/app.js
index dcc1e38..8216dcd 100644
--- a/src/static/app.js
+++ b/src/static/app.js
@@ -20,11 +20,31 @@ document.addEventListener("DOMContentLoaded", () => {
 
         const spotsLeft = details.max_participants - details.participants.length;
 
+        // Participants section
+        let participantsHTML = "";
+        if (details.participants.length > 0) {
+          participantsHTML = `
+            <div class="participants-section">
+              <strong>Participants:</strong>
+              <ul class="participants-list">
+                ${details.participants.map(email => `<li>${email}</li>`).join("")}
+              </ul>
+            </div>
+          `;
+        } else {
+          participantsHTML = `
+            <div class="participants-section no-participants">
+              <em>No participants yet. Be the first to sign up!</em>
+            </div>
+          `;
+        }
+
         activityCard.innerHTML = `
           <h4>${name}</h4>
           <p>${details.description}</p>
           <p><strong>Schedule:</strong> ${details.schedule}</p>
           <p><strong>Availability:</strong> ${spotsLeft} spots left</p>
+          ${participantsHTML}
         `;
 
         activitiesList.appendChild(activityCard);
diff --git a/src/static/styles.css b/src/static/styles.css
index a533b32..8de918e 100644
--- a/src/static/styles.css
+++ b/src/static/styles.css
@@ -142,3 +142,29 @@ footer {
   padding: 20px;
   color: #666;
 }
+
+.participants-section {
+  margin-top: 12px;
+  padding: 10px;
+  background-color: #e3eafc;
+  border-radius: 4px;
+}
+
+.participants-section strong {
+  color: #1a237e;
+}
+
+.participants-list {
+  margin: 8px 0 0 18px;
+  padding-left: 0;
+  list-style-type: disc;
+  color: #333;
+  font-size: 15px;
+}
+
+.no-participants {
+  background-color: #f9fbe7;
+  color: #757575;
+  font-style: italic;
+  border: 1px dashed #cfd8dc;
+}