diff --git a/Notebooks/Chap01/1_1_BackgroundMathematics.ipynb b/Notebooks/Chap01/1_1_BackgroundMathematics.ipynb
index b57eaef..a1556c2 100644
--- a/Notebooks/Chap01/1_1_BackgroundMathematics.ipynb
+++ b/Notebooks/Chap01/1_1_BackgroundMathematics.ipynb
@@ -67,7 +67,7 @@
       "source": [
         "# Define a linear function with just one input, x\n",
         "def linear_function_1D(x,beta,omega):\n",
-        "  # TODO -- replace the code lin below with formula for 1D linear equation\n",
+        "  # TODO -- replace the code line below with formula for 1D linear equation\n",
         "  y = x\n",
         "\n",
         "  return y"