diff --git a/example1/2-CalculateFeatures.ipynb b/example1/2-CalculateFeatures.ipynb
index 0346690..c5f25c3 100644
--- a/example1/2-CalculateFeatures.ipynb
+++ b/example1/2-CalculateFeatures.ipynb
@@ -14,7 +14,7 @@
    "source": [
     "---\n",
     "\n",
-    "**Rule 4: Turn Resuable Code into Functions Rather Than Duplicate Cells.** To avoid duplicating code, we have collected several functions in protvectors.py. These functions are also used in 4-Predict.\n",
+    "**Rule 4: Turn Reusable Code into Functions Rather Than Duplicate Cells.** To avoid duplicating code, we have collected several functions in protvectors.py. These functions are also used in 4-Predict.\n",
     "\n",
     "**Rule 5: Use the Notebook's Natural Structure to Organize Code and Reduce Clutter.** We use one cell for each distinct task.\n",
     "\n",