diff --git a/scripts/data/seed_amenity_data.py b/scripts/data/seed_amenity_data.py
index 1cf6a5b..19ba360 100644
--- a/scripts/data/seed_amenity_data.py
+++ b/scripts/data/seed_amenity_data.py
@@ -1,14 +1,16 @@
 #!/usr/bin/env python3
-"""Seed sample amenity data for development/testing.
+"""Seed sample data for development/testing.
 
-This script populates fact_amenities with sample data and updates
-dim_neighbourhood with population from fact_census, then runs dbt
-to rebuild the marts.
+This script:
+- Populates fact_amenities with sample data
+- Updates dim_neighbourhood with population from fact_census
+- Seeds median_age in fact_census where missing
+- Runs dbt to rebuild the marts
 
 Usage:
     python scripts/data/seed_amenity_data.py
 
-Run this after load_toronto_data.py if amenity data is missing.
+Run this after load_toronto_data.py to ensure notebooks have data.
 """
 
 import os
@@ -101,8 +103,33 @@ def update_population() -> int:
     return count
 
 
+def seed_median_age() -> int:
+    """Seed median_age in fact_census where missing."""
+    engine = create_engine(DATABASE_URL)
+
+    with engine.begin() as conn:
+        result = conn.execute(
+            text("SELECT id FROM public.fact_census WHERE median_age IS NULL")
+        )
+        null_ids = [row[0] for row in result]
+
+        if not null_ids:
+            print("No NULL median_age values found")
+            return 0
+
+        for census_id in null_ids:
+            age = random.randint(30, 50)
+            conn.execute(
+                text("UPDATE public.fact_census SET median_age = :age WHERE id = :id"),
+                {"age": age, "id": census_id},
+            )
+
+    print(f"Seeded median_age for {len(null_ids)} census records")
+    return len(null_ids)
+
+
 def run_dbt() -> bool:
-    """Run dbt to rebuild amenity marts."""
+    """Run dbt to rebuild marts."""
     dbt_dir = PROJECT_ROOT / "dbt"
     venv_dbt = PROJECT_ROOT / ".venv" / "bin" / "dbt"
     dbt_cmd = str(venv_dbt) if venv_dbt.exists() else "dbt"
@@ -118,7 +145,7 @@ def run_dbt() -> bool:
             "--profiles-dir",
             str(dbt_dir),
             "--select",
-            "+mart_neighbourhood_amenities",
+            "+mart_neighbourhood_amenities +mart_neighbourhood_demographics",
         ],
         cwd=dbt_dir,
         capture_output=True,
@@ -136,15 +163,16 @@ def run_dbt() -> bool:
 
 def main() -> int:
     """Main entry point."""
-    print("Seeding amenity data...")
+    print("Seeding development data...")
 
     seed_amenities()
     update_population()
+    seed_median_age()
 
     if not run_dbt():
         return 1
 
-    print("\nDone! Amenity data is ready.")
+    print("\nDone! Development data is ready.")
     return 0