diff --git a/sum23/lecture_materials/07_Strings/Exam_1_review.ipynb b/sum23/lecture_materials/07_Strings/Exam_1_review.ipynb
index 3f101d4030a41e02acc8f1f83430abcaa066acfb..29fa01afcf753b93cbe29f3c4543988661a4f1db 100644
--- a/sum23/lecture_materials/07_Strings/Exam_1_review.ipynb
+++ b/sum23/lecture_materials/07_Strings/Exam_1_review.ipynb
@@ -274,6 +274,49 @@
     "# Discuss: given two possible versions of a function (where one is correct),\n",
     "#          what is the general strategy for figuring out which one is correct?"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "d1ba721c",
+   "metadata": {},
+   "source": [
+    "## Iteration"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "851c3e95",
+   "metadata": {},
+   "source": [
+    "### Example 1 (Reimann sums)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "85e203c9",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Let's try the values from 1 to 5\n",
+    "start_x = 1\n",
+    "end_x = 5\n",
+    "total_area = 0\n",
+    "current_x = start_x\n",
+    "# Try out increasing values of width, make sure to comment the other width values\n",
+    "# delta_x = 1\n",
+    "delta_x = 0.1\n",
+    "# delta_x = 0.01\n",
+    "# delta_x = 0.001\n",
+    "\n",
+    "while current_x <= end_x:\n",
+    "    y = ???                # TODO: use f(x) defined previously\n",
+    "    rect_area = ???\n",
+    "    total_area += ???\n",
+    "    current_x += delta_x\n",
+    "    \n",
+    "print(\"Area found using approximation is:\", total_area)"
+   ]
   }
  ],
  "metadata": {