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

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.