diff --git a/04. Dimensionality Reduction.ipynb b/04. Dimensionality Reduction.ipynb
index 0b343ee..b9587b8 100644
--- a/04. Dimensionality Reduction.ipynb	
+++ b/04. Dimensionality Reduction.ipynb	
@@ -391,7 +391,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Or we can transorm all the data via the transform function."
+    "Or we can transform all the data via the transform function."
    ]
   },
   {
diff --git a/07. Regression.ipynb b/07. Regression.ipynb
index b49ed64..76f4d73 100644
--- a/07. Regression.ipynb	
+++ b/07. Regression.ipynb	
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Regression"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 1,
diff --git a/08. Graphs.ipynb b/08. Graphs.ipynb
index 2681bb4..5e6b4da 100644
--- a/08. Graphs.ipynb	
+++ b/08. Graphs.ipynb	
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Graphs"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 2,
diff --git a/09. Numerical Optimization.ipynb b/09. Numerical Optimization.ipynb
index f1e0208..dabf7e9 100644
--- a/09. Numerical Optimization.ipynb	
+++ b/09. Numerical Optimization.ipynb	
@@ -1,5 +1,12 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Numerical Optimization"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 1,