Y8 Python

• Computing
• Lower Secondary (Key Stage 3)

Python

On the road to code!

What is Python?

Python

• High level programming language
• Allows you to create your own programs
• Text based

Recall

Try these old recall questions on things you should know about programming

Code that runs one line after another is known as coding in...

1. Sequence
2. Selection
3. Iteration
4. Recursion

Code that repeats/loops is known as coding in...

1. Sequence
2. Selection
3. Iteration
4. Recursion

Code that only runs when a condition is met is known as coding in...

1. Sequence
2. Selection
3. Iteration
4. Recursion

An example of a loop in python would be:

1. print("this")
2. while x > 0 :
3. if x == 0 :
4. name = input("-->")

A value that is used by the program and can change is known as a...

1. constant
2. procedure
3. function
4. variable

Refresh

Time to refresh those skills

outputs

Used to output messages to the screen

In Python we use print

print ("hello world")

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Variables

An area in memory used to store a value the program will use.

The value is likely to change

Here are some examples in Python

name = "Dave"                      - Text 

health = 100                           - Integer

discount = False                  - Boolean  (True/False)

Inputs

We often use variables to store inputs from the user

In Python we use input

input ("Question the user will see as a prompt")

So to store a name we would use:

name = input ("What is your name  ? -->  ")

Checkpoint

Label the correct parts of this code (drag them)

filmpref = input("What kind of films do you like? ")

Variable

This is aplaceholder for a value that will change in the program

function

This is a calling a pre-made function from the python library

All functions are followed by brackets ()

Sometimes information is written between these brackets

This is called a "parameter"

Parameter

This is a text prompt which is the parameter of the input function.

It will pop up on screen before taking an input from the user

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CORRECT

CAUSE AN ERROR

print = ("Hello")

Print("Yes!")

print("this one)

name = imput("what is your name")

name = input("what is your name")

print("this text")

fav colour = "Green"

age = 10

print("Hello", name)

print("Bye",name")

IF/ELIF/ELSE

When we need to make a decision in a program we use a selection statement .

In Python we use if  elif  and  else

Let's look at some coded examples...

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Now Try Yourself

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In python you must write IF, ELIF and ELSE in capital letters

1. TRUE
2. FALSE

After every if, elif and else statement you put ...

1. ;
2. }
3. :
4. #

An elif part of the code will only run if the if part was not met

1. True
2. False

an if statement must always have an else component

1. True
2. False

which of the following if statements would cause an error

1. if name != "Fred":
2. if password == guess:
3. if name = "Bobby":
4. if age >= 18 :

While Loops

Sometimes you need the computer to repeat steps until a certain condition has been met

In Python we use while  and  for

Let's look at some coded examples of a while loop...

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Your Turn

Making a quiz question program

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Lists

When we code we need to store things

A variable is one example

Sometimes we need to store lots of things that are related in someway.  

We call these places "Data Structures"

Lists

In python one of the most used data structures is a list

Lists are used to store similar data, one item after another

For example:

• items you need to buy from a shopping list
• names of students in a class

A list is an example of a 1 Dimensional array.

Lists?
What could we store?

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Removing items

To remove items from a list is simple

we use:

• listname.remove("itemname")

Bread

Milk

Cheese

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Challenges

Create a program that can do the following:

• Offer the user 3 options

1. Add to the shopping list
2. Remove from the shopping list
3. print the shopping list to the screen

• The program should also:

1. repeat and display the three options each time
2. take user input for new items and items that need removing
3. prevent users entering options that are not allowed
4. The program should exit if the user ever enters an "x"

Solution code

Link to solution