Rachel

These are my edits to lab 1. I tried to make the lab more consistent and slightly shorter (based on feedback from students). Here are the big changes:
1. I made some of the online resources "required reading" and deleted corresponding sections of the lab because I found the online resources clearer. 
2. I deleted a few homework exercises that were ambiguous (also with the goal of making the lab slightly shorter).
3. I deleted most (not all!) text and exercises about mutable vs. immutable objects because I felt this topic was unduly emphasized. I think this is an (important) detail that most students will not be able to absorb in their first exposure to Python.
4. I added some other strategies to the section "Learning Python."
Typically, we only use the >>> prompt if it is part of an interactive session (we expect them to type into the python console).  We also use the listings environment to show short listings of code to discuss (as this case is).  In the python interpreter, it would be waiting for more input because of the colon.