If you use the computers in the Engineering Labs (Seaton 54 or Fiedler 1092), and if you open a command window to start the Python interpreter, please note that you must type into the command window first,

  set path=C:\Python23

and then you can type

  python

to start the interpreter. (The reason for the extra command is explained at the end of the Chapter 2 Lecture Notes --- the PATH variable in the computers is not set to locate Python automatically, so you must state where Python lives on the computer's disk. So it goes.)