Python - Lesson 2

• Computing
• Lower Secondary (Key Stage 3)

Python - Lesson 2

KO: To be-able to use selection statements with variables.

All

• To be-able to use variables in programming.
• To be-able to use print statements in programming.

Most 

• To be-able to explain why selection statements are used to validate a users input.

Some

• To be-able to create code, using variables and selection statements to validate an input.

Thinking back to last weeks lesson.

What is the purpose of programming?

What is the correct version of code?

1. print("Hello World")
2. print"(Hello World")
3. print((Hello World))
4. print(Hello World")

What is a Variable?

In programming, a variable is a named storage location in a computer's memory that can hold a value. The value stored in a variable can be changed throughout the program's execution, hence the term "Variable".

Recap - Variables

Using this example, I want you to go and create your own sentence, using 'Variable'.

Example

name = bob 

print("Hello my name is", name)

click here

Recap - Variables

Storing an 'Input' inside a 'Variable'.

Example 

name = input("Please can you enter your name?")

school = input("Please can you enter your school?")

print("Hello, your name is", name, "and you go to", school)

click here

Debugging Task

Can you find out what is wrong with the code?

First person to correct all mistakes, wins

A GOLDEN TICKET!

Click here

What would the output be for this code?

food = "pizza"
print("orange")

1. print pizza
2. food
3. orange
4. pizza

What would the output be for this code?

myname = bob
name = input("please enter your name")
print(name)

1. bob
2. name
3. john
4. myname

Selection Statements

Selection allows us to make decisions in our programs.

The code we use, are IF statements.

Below is an example

IF I want to play on my PS5 THEN

I need to switch the PS5 on

Else

I leave the PS5 switched off.

Example

IF Statements

Let's take a look at how it works.

Click here

Indentation

• You may notice in my code, that some of the lines have been indented.
• There is a reason for this.
• Python requires indentation for the syntax.
• Indentation signifies the start and end of a block of code.
• Programs will not run.

Comparison Operators

Challenge Time!

Golden Ticket is up for grabs...

Scenario

Age must be 18 to go into a club.

I want to go to a club, but I want to check whether I am old enough. If I am old enough, the program must say "You can go to the party" and if I am not old enough, the program must say, "You can't go to the party".

Comparison Operator you must use is -  >=

Answer

What is the comparison operator for not equal to?

1. !=
2. <=
3. >=
4. ==

What does a selection statement do?