Random thoughts about the HW
* Make sure to save and send hw0.py, not a file showing how the program ran.
  I want the actual code so I can run it and make sure it works right.
* Save your file as something ending with .py.  That tells Python that it is a
  python file.
* Many people indicated they expected an A with less than 5 hours per week.
  That can happen for a few people perhaps, but not as many as indicated this.
  If you want an A, you're probably going to need to commit more than 5 hours
  per week.  Better to start off ahead then try to catch up later.
* Those who started early and got feedback - good job, well done!

Readings
* Listed on the website.
* You need to do them!  Just listening in class is not enough.
* How to do the readings - have Python/IDLE open while you read, and type 
  things in as you go.

Learning new parts of Python
* Look at the code and think about what you think it will do.
* Then type it in and see what it actually does.
* If it did not do what you thought, read again about what it is 
  supposed to do.

Python errors
* Everything has to be just the way python expects it. 
* If it prints an error message, try to read it.  Sometimes it tells you 
  what the problem is, and sometimes it doesn't.

In-class activities
* Write a program to take the average of 3 numbers (use + and /).
* Now take the average of 3 numbers that you get from the user (use raw_input).
* Now after you have the average, set a Boolean variable saying whether
  the average is greater than or equal to 90 (use >=).
* Now print a statement saying whether the average gives an A or not
  (use print, if)
* Working on the homework
* If you are done with the homework already, start working through things
  you don't know yet in the Think Python book and the Python Tutorial.
  - The sooner you learn more, the more you can do sooner.
  - Can you do the greater than/less than game?
  - Can you put the grading example from class into a loop to keep asking
    for grades until they type q, then take the average of all that?

Outline and content for today ...
* Different types of data/variables and ways to deal with them.
  - string/text
  - numbers (floating point, integer)
  - Boolean (True or False)
  - lists
  - dictionaries
* Variables - keeping some data for later use.
  - saving into a variable: use =
  - getting from a variable: use on the other side of equal, in a print, or 
    in an if, or other places.
* print
  - print("Hello world.")
  - print "Hello World."
  - print(str(10))
  - print 10
* Python/IDLE command line
  - type things in one line at a time and see them executed one line at a time.
* Python file, and Run/Run Module
  - run all the lines in the file, starting with the first.
* Comments
  - any line starting with # is ignored by Python, but provides some 
    explanation for any person reading the python file.
* String/text
  - "this is a string"
  - "you combine strings" + " by using plus in between them"
  - message = "saving a string into a variable"
  - message = str(10.0)
  - message = 'you can also use single quotes.'
* Numbers
  - saving a number into a variable is like this: x = 10
  - integer is without a decimal point, so if needed things are rounded
    ( so x = 10/3 will make x have the value 3)
  - floating point is with the decimal point, so x=10/3.0 will make have 
    the value 3.33333333
  - can convert between integer, floating point, and string using the 
    type conversion functions str, float, int.
    - any time you use one of those you put the function name, then 
      whatever you want to do it to in ().  so x = int("5") puts the number 
      5 into x.
  - doing math: use * + - / %
    - division with integers: x = 11 / 3 is rounded, so will give the answer
      as 3.  if you want the remainder you use %, so x = 11 % 3 gives the 
      remainder after dividing by 3, so 2.
* Boolean
  - things that are either True or False.  
  - The basic values are either True or False, and you can combine them 
    with and, or, not.  So True or False will evaluate to True.
  - Can use comparisons < <= > >= == <>
    (less than, less than or equal to, greater than, greater than or equal to,
    equal to, not equal to).
  - So (1 == 2) is False, (1 <> 2) is True, ...
* raw_input
  - x = raw_input("Type something: ")
    That displays Type something:, wait for the user to type something and 
    press enter, and puts that into x, making x a string variable.
  - to get a number from the user, you convert it to an int or float, like
    number = float(raw_input("Type a number: "))
* python file versus running the python file
  - When you are running the python file, you are the "user".  The user 
    normally does not look at the actual program, they just use it.
  - When you are working on the python file, you are the programmer.  You are
    creating a program so that it does something useful for the user (e.g.,
    you are making a game for them to use).
* lists and dictionaries
  - keeping more than one value, we'll talk about that later...