Instructor: To open finder from a terminal, we can simply say open and give it a directory, such as doc. Open is like double clicking. It opens its argument in the default app for its file type as specified in launch services. The default app for a folder is finder.
What about opening a new terminal from the finder? If you haven't done it already, go to the finder menu, services, services preferences, and scroll down until you find new terminal at folder. Enable it.
Preferably give it a keyboard shortcut. I have chosen command nine, but you can pick anything that isn't already in use.
If I click on a folder and hit my shortcut, it opens a new terminal window at that folder. By the way, as I said, if I say open a file, it will open it in the default app for that file, which in this case is preview.
If I give it a -a option to open, and specify an app just by name without its path name, it will open the arguments in that app. Furthermore, if I say open and -a and the name of an app, without passing it an argument, it will open the app.