I am giving this answer on behalf of Bhavi.  It is always a good idea to type the commands exactly as shown in the Spoken Tutorial.  It is possible that some commands may also work with uppercase, but not all commands may work.  This will be especially true for flags, about which you will learn later.

Answering on behalf of Ambika: This is explained in a subsequent spoken tutorial.  For example, it is explained in the spoken tutorial Redirecting Streams and Pipes.