diff --git a/README.md b/README.md
index a99496e..a28b447 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ The book is written as a collection of Jupyter Notebooks, an interactive, browse
 
 ### GitHub
 
-GitHub is able to render the notebooks directly. The quickest way to view a notebook is to just click on them above. Chapters names are prefaced with numbers to indicate their order 01_gh_filter.ipynb, and so on. Rendering may be a bit slow or imperfect.
+GitHub is able to render the notebooks directly. The quickest way to view a notebook is to just click on them above. Chapters names are prefaced with numbers to indicate their order 01_gh_filter.ipynb, and so on. Rendering may be a bit slow or imperfect. Notebooks are rendered statically - you can read them, but not modify or run the code.
 
 ### binder
 
@@ -27,7 +27,7 @@ I am experimentally trying a new service, binder. binder serves interactive note
 
 ### nbviewer
 
-The website http://nbviewer.org provides an Jupyter Notebook server that renders notebooks stored at github (or elsewhere). The rendering is done in real time when you load the book. You may use [*this nbviewer link*](http://nbviewer.ipython.org/github/rlabbe/Kalman-and-Bayesian-Filters-in-Python/blob/master/table_of_contents.ipynb) to access my book via nbviewer. If you read my book today, and then I make a change tomorrow, when you go back tomorrow you will see that change. 
+The website http://nbviewer.org provides an Jupyter Notebook server that renders notebooks stored at github (or elsewhere). The rendering is done in real time when you load the book. You may use [*this nbviewer link*](http://nbviewer.ipython.org/github/rlabbe/Kalman-and-Bayesian-Filters-in-Python/blob/master/table_of_contents.ipynb) to access my book via nbviewer. If you read my book today, and then I make a change tomorrow, when you go back tomorrow you will see that change. Notebooks are rendered statically - you can read them, but not modify or run the code.
 
 ### SageMathCloud