diff --git a/13-Smoothing.ipynb b/13-Smoothing.ipynb
index 22ccf45..d439102 100644
--- a/13-Smoothing.ipynb
+++ b/13-Smoothing.ipynb
@@ -415,7 +415,7 @@
     "\n",
     "* Fixed Interval Smoothing\n",
     "\n",
-    "This is a batch processing based filter. This filter waits for all of the data to be collected before making any estimates. For example, you may be a scientist collecting data for an experiment, and don't need to know the result until the experiment is complete. A fixed interval smoother will collect all the data than estimate the state at each measurement using all available previous and future measurements. If it is possible for you to run your Kalman filter in batch mode it is always recommended to use one of these filters a it will provide much better results than the recursive forms of the filter from the previous chapters.\n",
+    "This is a batch processing based filter. This filter waits for all of the data to be collected before making any estimates. For example, you may be a scientist collecting data for an experiment, and don't need to know the result until the experiment is complete. A fixed interval smoother will collect all the data, then estimate the state at each measurement using all available previous and future measurements. If it is possible for you to run your Kalman filter in batch mode it is always recommended to use one of these filters a it will provide much better results than the recursive forms of the filter from the previous chapters.\n",
     "\n",
     "\n",
     "* Fixed Lag Smoothing\n",