Tutorial says test it in Scratch Pad but Scratch Pad does not appear?

I am taking the tutorial/formula
Build an App with Navigation and Routing - Part 1 and Part 2. At the bottom of the documentation it says
Try this tutorial out below in the Scratch pad:
I do not see the Scratch Pad or do not know how to use it. I have a similar app that is not working and would like to see how it works in the scratch pad.
Any suggestions?