diff --git a/part-4.ipynb b/part-4.ipynb
index c9abaa1..6d9dd75 100644
--- a/part-4.ipynb
+++ b/part-4.ipynb
@@ -1,7 +1,7 @@
 {
  "metadata": {
   "name": "",
-  "signature": "sha256:640caa4f1507ed924c3e826c02125468a1dc8314809695aa3b1b04bcae642559"
+  "signature": "sha256:7b5c09563e39ddf2ede88b8ff357dcdc654af16292c9c86e3bca2fbf703f64c2"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -518,6 +518,8 @@
       "\n",
       "Tuples are similar to lists except they're immutable, which means we can't change them after they've been made.\n",
       "\n",
+      "One real world use of tuples is to hold one particular record within a complex file. For example, a stock holding or a restaurant inventory.\n",
+      "\n",
       "Tuples are comma-separated lists:"
      ]
     },
@@ -525,17 +527,24 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "stuff = (1, 2, \"hello\")"
+      "food = (\"cones\", 100, 3.79)"
      ],
      "language": "python",
      "metadata": {},
      "outputs": []
     },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "This is sometimes called packing a tuple."
+     ]
+    },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "stuff"
+      "food"
      ],
      "language": "python",
      "metadata": {},
@@ -545,7 +554,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "type(stuff)"
+      "type(food)"
      ],
      "language": "python",
      "metadata": {},
@@ -562,7 +571,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "stuff = 1, 2, 3"
+      "food = \"sprinkles\", 10, 4.99"
      ],
      "language": "python",
      "metadata": {},
@@ -572,7 +581,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "stuff"
+      "food"
      ],
      "language": "python",
      "metadata": {},
@@ -589,7 +598,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "stuff[2] = 3"
+      "food[2] = 3"
      ],
      "language": "python",
      "metadata": {},
@@ -612,6 +621,26 @@
      "metadata": {},
      "outputs": []
     },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "empty"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "type(empty)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
     {
      "cell_type": "markdown",
      "metadata": {},
@@ -623,7 +652,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "things = (3)"
+      "food = (3)"
      ],
      "language": "python",
      "metadata": {},
@@ -633,7 +662,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "things"
+      "food"
      ],
      "language": "python",
      "metadata": {},
@@ -643,7 +672,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "type(things)"
+      "type(food)"
      ],
      "language": "python",
      "metadata": {},
@@ -660,7 +689,7 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "things = (3,)"
+      "food = (3,)"
      ],
      "language": "python",
      "metadata": {},
@@ -670,11 +699,107 @@
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "things"
+      "food"
      ],
      "language": "python",
      "metadata": {},
      "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "type(food)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Sometimes, unpacking a tuple is also desired."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "yummies = [(\"cones\", 100, 3.79), (\"sprinkles\", 10, 4.99), (\"hot fudge\", 8, 3.29), (\"nuts\", 6, 8.99)]"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "yummies[2]"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "name, amount, price = yummies[2]"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "print(\"Our ice cream shop serves \" + name + \".\")"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "print(\"The shop's inventory value for \" + name + \" is $\" + str(amount * price) + \".\")"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "print(\"All this food talk is making me hungry for \" + yummies[3][0] + \".\")"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Why not always use lists instead of tuples? Tuples use less storage space than a list. So if you are reading 1000s of small records from a file, a tuple can be an efficient way to go.\n",
+      "\n",
+      "A practical learning tip: When learning a new language, there are many new terms and concepts. Sometimes it is helpful to see a bigger picture of how everything comes together. I'm a lover of \"Table of Contents\" since I can scan the big picture and see where something like a tuple fits in. The official Python tutorial has a very good [Table of Contents]( https://docs.python.org/3.4/tutorial/index.html), and I sometimes take 5 minutes to just click and explore something new to me.\n",
+      "\n",
+      "Wow! We've come a long way today. "
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
     }
    ],
    "metadata": {}