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Student objective: How are
variables set up and used in
Bell ringer: Where we using python
in the interactive mode or script
mode on Friday?
Set Up Grade Sheet
KWL (5)
Syllabus (5)
Communication compact (5)
Computer Parts Project (25)
Vocab (10)
Print Project (10)
Number Guessing Game (10)
• Notes on python basics and variables
• Assignments: programming
Bell Ringer Answer: Interactive
Interactive mode-program and run in IDLE
• Immediate feedback
• Not designed to save and run later
Script Mode Write the program
• Write program and save it to use later
Let’s try it
To write a python program and save it:
Open Python IDLE
Click on file—New Window
Type your program in
File—Save as .py in documents folder of
• Click Run—Run Module
• IDLE pops back up with program
Syntax Errors
• Spelling/grammar
• Picked up prior to running program
Runtime errors
• Occur during execution of program
• 4-line error message starting with Traceback
• Tells where the error is and what it is
Semantic errors
• Don’t use commas with numbers or will get
this error
• Code will run but be wrong
• Input
• Processing
• Output
Variables (values)
• Integers: int
numbers no decimal points
• Strings: str use single or double quotation
character or string of
characters: letters, numbers,
• Long string: str multi-line string: triple
• Floating point: float decimal numbers
Color coding
Special words, like print: orange
Strings: green
Output: blue
Comments: red
Used to explain code
Invaluable to programmers
Are not executable by the computer
# symbol is used to denote the start of a
Blank Lines and Spacing
Blank lines
• Are ignored by the computer
• Can make program easier to read
• is critical and will create errors if not followed
• Tells where blocks of code start and where they
• Convention: 4 spaces in
• Necessary for if statement
Naming Variables
• If you don’t know the type of variable, you can find out by
• Writing in the IDLE:
• type ( variable ) then click return (Remember strings in
quotes, numbers not)
• You can name variables (words, numbers) to input into
memory (Name it so you can use it)
• Teacher = “Mr. Morton”
• First = 5
• *You can have more than one name for one thing
• *You can also change names
Rules for naming variables:
• Can use letters, numbers and underscore
• Case sensitive
• Must start with letter or underscore (Not a
good idea to start with underscore), NOT A
• Make variables names clear—don’t try to
• Adding strings like “cat” + “dog”
• Results would be catdog
Using variables
Variables can also be made to equal themselves:
>>Score = 7
>>Score = Score
>>Score = Score + 1
>>print Score Hit return
Generates >>8
Useful to increment or decrement a value