diff --git a/content/code/python/abstracting-plot.py b/content/code/python/abstracting-plot.py
index c2f7303..79a77a5 100644
--- a/content/code/python/abstracting-plot.py
+++ b/content/code/python/abstracting-plot.py
@@ -40,11 +40,11 @@ def plot(column, label, location, color, compute_mean):
 # read data
 data = pd.read_csv("weather_data.csv")
 
-# combine 'date' and 'time' into a single datetime column
-data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+# combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-# set datetime as index for convenience
-data = data.set_index("datetime")
+# set 'recorded_at' as index for convenience
+data = data.set_index("recorded_at")
 
 
 for month in ["2024-01", "2024-02", "2024-03"]:
diff --git a/content/code/python/add-iteration.py b/content/code/python/add-iteration.py
index ea262f8..162fb68 100644
--- a/content/code/python/add-iteration.py
+++ b/content/code/python/add-iteration.py
@@ -5,12 +5,11 @@
 # read data
 data = pd.read_csv("weather_data.csv")
 
-# combine 'date' and 'time' into a single datetime column
-data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
-
-# set datetime as index for convenience
-data = data.set_index("datetime")
+# combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
+# set 'recorded_at' as index for convenience
+data = data.set_index("recorded_at")
 
 for month in ["2024-01", "2024-02", "2024-03"]:
     data_month = data.loc[month]
diff --git a/content/code/python/cli.py b/content/code/python/cli.py
index 2278414..dbc9e6a 100644
--- a/content/code/python/cli.py
+++ b/content/code/python/cli.py
@@ -10,11 +10,11 @@
 def read_data(file_name):
     data = pd.read_csv(file_name)
 
-    # combine 'date' and 'time' into a single datetime column
-    data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+    # combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+    data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-    # set datetime as index for convenience
-    data = data.set_index("datetime")
+    # set 'recorded_at' as index for convenience
+    data = data.set_index("recorded_at")
 
     return data
 
diff --git a/content/code/python/initial-version-with-mean.py b/content/code/python/initial-version-with-mean.py
index 6fe191e..558db6c 100644
--- a/content/code/python/initial-version-with-mean.py
+++ b/content/code/python/initial-version-with-mean.py
@@ -5,13 +5,13 @@
 # read data
 data = pd.read_csv("weather_data.csv")
 
-# combine 'date' and 'time' into a single datetime column
-data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+# combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-# set datetime as index for convenience
-data = data.set_index("datetime")
+# set 'recorded_at' as index for convenience
+data = data.set_index("recorded_at")
 
-# keep only january data
+# keep only january data using datetime period indexing
 january = data.loc["2024-01"]
 
 fig, ax = plt.subplots()
diff --git a/content/code/python/initial-version-with-precipitation.py b/content/code/python/initial-version-with-precipitation.py
index a50f079..97fad53 100644
--- a/content/code/python/initial-version-with-precipitation.py
+++ b/content/code/python/initial-version-with-precipitation.py
@@ -5,13 +5,13 @@
 # read data
 data = pd.read_csv("weather_data.csv")
 
-# combine 'date' and 'time' into a single datetime column
-data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+# combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-# set datetime as index for convenience
-data = data.set_index("datetime")
+# set 'recorded_at' as index for convenience
+data = data.set_index("recorded_at")
 
-# keep only january data
+# keep only january data using datetime period indexing
 january = data.loc["2024-01"]
 
 fig, ax = plt.subplots()
diff --git a/content/code/python/initial-version.py b/content/code/python/initial-version.py
index b22db27..9f0f7c0 100644
--- a/content/code/python/initial-version.py
+++ b/content/code/python/initial-version.py
@@ -5,13 +5,13 @@
 # read data
 data = pd.read_csv("weather_data.csv")
 
-# combine 'date' and 'time' into a single datetime column
-data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+# combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-# set datetime as index for convenience
-data = data.set_index("datetime")
+# set 'recorded_at' as index for convenience
+data = data.set_index("recorded_at")
 
-# keep only january data
+# keep only january data using datetime period indexing
 january = data.loc["2024-01"]
 
 fig, ax = plt.subplots()
diff --git a/content/code/python/small-improvements.py b/content/code/python/small-improvements.py
index 322878b..d02883a 100644
--- a/content/code/python/small-improvements.py
+++ b/content/code/python/small-improvements.py
@@ -5,11 +5,11 @@
 def read_data(file_name):
     data = pd.read_csv(file_name)
 
-    # combine 'date' and 'time' into a single datetime column
-    data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+    # combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+    data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-    # set datetime as index for convenience
-    data = data.set_index("datetime")
+    # set 'recorded_at' as index for convenience
+    data = data.set_index("recorded_at")
 
     return data
 
diff --git a/content/code/python/testing.py b/content/code/python/testing.py
index 56d406d..c631434 100644
--- a/content/code/python/testing.py
+++ b/content/code/python/testing.py
@@ -6,11 +6,11 @@
 def read_data(file_name):
     data = pd.read_csv(file_name)
 
-    # combine 'date' and 'time' into a single datetime column
-    data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+    # combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+    data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-    # set datetime as index for convenience
-    data = data.set_index("datetime")
+    # set 'recorded_at' as index for convenience
+    data = data.set_index("recorded_at")
 
     return data
 
diff --git a/content/code/python/towards-pure.py b/content/code/python/towards-pure.py
index 1cb0ddc..1d7933f 100644
--- a/content/code/python/towards-pure.py
+++ b/content/code/python/towards-pure.py
@@ -5,11 +5,11 @@
 def read_data(file_name):
     data = pd.read_csv(file_name)
 
-    # combine 'date' and 'time' into a single datetime column
-    data["datetime"] = pd.to_datetime(data["date"] + " " + data["time"])
+    # combine 'date' and 'time' into a single column 'recorded_at' as type datetime
+    data["recorded_at"] = pd.to_datetime(data["date"] + " " + data["time"])
 
-    # set datetime as index for convenience
-    data = data.set_index("datetime")
+    # set 'recorded_at' as index for convenience
+    data = data.set_index("recorded_at")
 
     return data