Python Conditionals

Python Conditionals

by Jason Davis

​What's Up?

Essential Question​

How can a program make decisions about whether or not to run code?

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​Objective

I can write code that decides whether or not to perform an action

Define: conditional

• Code structure

• Lets us make decisions

• Do a section of code or skip it

• "If yes, then do something"

• Example: "If it is raining, then I'll bring an umbrella."

Multiple Choice

What best describes a conditional?

• I will do what I want

• If the answer is no, then I'll do something

• If it doesn't snow I'll wear my snow boots to school

• If the answer is yes, then I'll do something

Define: if-clause/then-block

• if-clause in code is the condition:

• if-clause decides whether or not to proceed with the then-block

• ​

  then-block has at least one line of code

  then-block can either be executed or skipped depending on the if-clause

Multiple Choice

Which part of a conditional decides whether or not to skip the then-block?

• if-clause

• then-block

• input statement

• print statement

Structure of a Conditional

• Two parts: if-clause and then-block

• then-block is indented under if-clause

• ​Words go in quote marks, numbers don't

• ​Don't forget the colon!

Multiple Choice

What happens to the then-block if the condition in the if statement isn't true?

• It runs either way

• It gets skipped

• You will receive an error message

• The program asks the user the input a new answer

Multiple Choice

What happens to the then-block you forget the colon after the if-clause

• It runs either way

• It gets skipped

• You will receive an error message

• The program asks the user the input a new answer

• Define: comparison operators

• ​Comparison Operators are the symbols that help determine if a conditional is true or false. You might recognize them from your math class - but with a twist!

• ​

  1. < less than

  2. <= less than or equal to

  3. > greater than

  4. >= greater than or equal to

  5. == equal to

  6. != not equal to

Fill in the Blanks

What is the comparison operator symbol for greater than?

Fill in the Blanks

What is the comparison operator symbol for equal to?

What is a valid condition?

• Part of the if-clause

• Asks a yes or no question

• Usually contains an expression (a comparison of value)

• Often uses comparison operators

Multiple Choice

True or false: The if-clause HAS to use numbers for comparison.

• True

• False

I'm just using this slide so there aren't two questions in a row. It's good, right?​

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Poll

On a scale of 1-5, where are you on conditionals?

• 1

  Conditionals? Never heard of them.

• 2

  I am strugling to understand the vocabulary and the coding.

• 3

  I understand the vocabulary, but I'm struggling with the coding.

• 4

  I am good with the coding, but still fuzzy on the vocab

• 5

  I understand everything and I can code programs with conditionals by myself.