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appendix/01/README.md

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 ## How to run the examples on a Raspberry Pi?
 
-A few years ago, assuming that everybody has a computer with a graphical processing unit was a long shot. Now, most computers have a GPU, but is still a high bar for a requirement in a workshop or class, for example. 
+A few years ago, assuming that everybody has a computer with a graphical processing unit was a long shot. Now, most computers have a GPU, but it's still a high bar for a requirement in a workshop or class, for example. 
 
 Thanks to the [Raspberry Pi Foundation](http://www.raspberrypi.org/) a new type of small and cheap generation of computers (around $35 each) has found its way into classrooms. More importantly for the purposes of this book, the [Raspberry Pi](http://www.raspberrypi.org/) comes with a decent Broadcom GPU that can be accessed directly from the console. I made a [flexible GLSL live coding tool call **glslViewer**](https://github.com/patriciogonzalezvivo/glslViewer) that runs all the examples in this book. This program also has the ability to update automatically when the user saves a change to their code. What does this mean? You can edit the shader and every time you save it, the shader will be re-compile and render for you.