diff --git a/04-One-Dimensional-Kalman-Filters.ipynb b/04-One-Dimensional-Kalman-Filters.ipynb
index e999d51..6e1e83a 100644
--- a/04-One-Dimensional-Kalman-Filters.ipynb
+++ b/04-One-Dimensional-Kalman-Filters.ipynb
@@ -2164,7 +2164,7 @@
    "source": [
     "## Comparison with g-h and discrete Bayes Filters\n",
     "\n",
-    "Now is a good time to be understand the differences between these three filters in terms of how we model errors. For the g-h filter we modeled our measurements as shown in this graph:"
+    "Now is a good time to understand the differences between these three filters in terms of how we model errors. For the g-h filter we modeled our measurements as shown in this graph:"
    ]
   },
   {