diff --git a/docs/learning/09 Adding Documentation.ipynb b/docs/learning/09 Adding Documentation.ipynb
index 9ee476e..8de63c1 100644
--- a/docs/learning/09 Adding Documentation.ipynb	
+++ b/docs/learning/09 Adding Documentation.ipynb	
@@ -95,8 +95,10 @@
     "We add the extensions by adding this to `conf.py` too:\n",
     "```python\n",
     "extensions = [\n",
-    "    'sphinx.ext.autodoc',\n",
-    "    'sphinx.ext.napoleon',\n",
+    "    'sphinx.ext.autodoc',   # for generating documentation from the docstrings in our code\n",
+    "    'sphinx.ext.napoleon',  # for parsing Numpy and Google stye docstrings\n",
+    "    'sphinx.ext.mathjax',   # for equation rendering\n",
+    "\n",
     "]\n",
     "```"
    ]