Lesson 07: Python Lists: Create, Access, Change, Add & Remove

Phase 1 of 9

Lesson Introduction

Imagine you are keeping track of your five favourite fruits. You could store each one in a separate variable:

python

fruit1 = "apple"
fruit2 = "banana"
fruit3 = "cherry"
fruit4 = "mango"
fruit5 = "grape"

That works · but what if you had 500 fruits? Or what if the number of fruits changes every day? Creating 500 individual variables would be a nightmare.

Python solves this with a list · a single container that can hold as many items as you need, all under one name. Lists are one of the most important and most-used tools in all of Python. You will use them in data analysis, web development, automation, science, games, finance, and almost every real-world Python project.

By the end of this lesson you will be able to:

Create lists and understand exactly what they are
Access any item in a list using its index number
Change items that are already in a list
Add new items to a list
Remove items from a list
Build a working mini-project that uses all five skills together

✏️ Your Task

Practise what you just learned about Lesson Introduction. Open your editor, type the examples above by hand, modify them, and observe what changes.

Phase 2 of 9

Prerequisite Concepts

Before we start, here are the small things you need to already know. If any of these feel unfamiliar, re-read your earlier lessons first.

Concept	Quick reminder
Variables	`name = "Alice"` · a labelled box that stores a value
`print()`	Displays output to the screen
Data types	`str` (text), `int` (whole number), `float` (decimal), `bool` (`True`/`False`)
`len()`	Counts how many characters are in a string · we will use it to count list items today

No other prior knowledge is needed. Everything else is taught from scratch right here.

✏️ Your Task

Practise what you just learned about Prerequisite Concepts. Open your editor, type the examples above by hand, modify them, and observe what changes.

Phase 3 of 9

Part 1 · What Is a Python List?

1.1 The Real-World Analogy

Think of a shopping list on paper:

code

1. Milk
2. Eggs
3. Bread
4. Butter

Each item has a position (1st, 2nd, 3rd, 4th). You can add a new item at the bottom. You can cross off (remove) something you already bought. You can change "Butter" to "Olive Oil".

A Python list works in exactly the same way · except it lives inside your program.

1.2 The Technical Definition

A Python list is:

An ordered collection of items (items always stay in the order you put them, unless you change that order)
Changeable (you can add, remove, and edit items after creating the list)
Allows duplicates (the same value can appear more than once)
Written with square brackets [] and items separated by commas ,

1.3 Creating Your First List

Syntax:

python

list_name = [item1, item2, item3]

Simple Example 1 · A list of fruits (strings):

python

fruits = ["apple", "banana", "cherry"]
print(fruits)

Expected output:

code

['apple', 'banana', 'cherry']

What happened? Python stored three text values inside one variable called fruits. Notice the square brackets and the commas.

Simple Example 2 · A list of numbers:

python

scores = [95, 87, 76, 100, 60]
print(scores)

Expected output:

code

[95, 87, 76, 100, 60]

Simple Example 3 · A list of mixed data types:

Python lists can hold different types in the same list:

python

mixed = ["Alice", 25, True, 3.14]
print(mixed)

Expected output:

code

['Alice', 25, True, 3.14]

Thinking prompt: Why would storing different types together be useful? Imagine a student record: name (string), age (int), passed (bool), GPA (float).

1.4 How Many Items? · `len()`

The built-in len() function counts the number of items in a list.

python

fruits = ["apple", "banana", "cherry"]
print(len(fruits))

Expected output:

code

1.5 Lists Can Hold Other Lists (Nested Lists)

A list can even contain another list inside it. This is called a nested list.

python

matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
print(matrix)

Expected output:

code

[[1, 2, 3], [4, 5, 6], [7, 8, 9]]

We will not go deep into nested lists today, but it is important you know they exist.

1.6 The `list()` Constructor

You can also create a list using the list() function:

python

colours = list(("red", "green", "blue"))
print(colours)

Expected output:

code

['red', 'green', 'blue']

Note: Notice the double parentheses (( )) · the inner () creates a tuple (another collection type), and list() converts it into a list.

1.7 List Data Type

To confirm something is a list, use type():

python

fruits = ["apple", "banana", "cherry"]
print(type(fruits))

Expected output:

code

<class 'list'>

✏️ Your Task

Practise what you just learned about What Is a Python List?. Open your editor, type the examples above by hand, modify them, and observe what changes.

Phase 4 of 9

Part 2 · Accessing List Items

2.1 What Is an Index?

Every item in a list has a position number called an index.

Analogy: Think of seats in a cinema row. Seat 0 is the first seat, seat 1 is the second, and so on.

Python indexes start at 0, not 1. This is called zero-based indexing and is used in almost all programming languages.

code

List:   ["apple", "banana", "cherry", "mango", "grape"]
Index:      0         1         2        3        4

2.2 Accessing a Single Item

Use the list name followed by the index number inside square brackets:

python

fruits = ["apple", "banana", "cherry"]
print(fruits[0])   # First item
print(fruits[1])   # Second item
print(fruits[2])   # Third item

Expected output:

code

apple
banana
cherry

Common beginner mistake: Trying fruits[3] when only 3 items exist (indexes 0, 1, 2). This causes an IndexError: list index out of range.

Corrected version:

python

fruits = ["apple", "banana", "cherry"]
print(len(fruits))     # 3 items → valid indexes are 0, 1, 2
print(fruits[2])       # Correct: last item
# print(fruits[3])     # WRONG: would crash

2.3 Negative Indexing

Python also allows negative indexes. A negative index counts from the end of the list.

code

List:   ["apple", "banana", "cherry"]
Neg:       -3        -2        -1

-1 is always the last item. -2 is second from last. And so on.

python

fruits = ["apple", "banana", "cherry"]
print(fruits[-1])   # Last item
print(fruits[-2])   # Second from last
print(fruits[-3])   # Third from last (same as index 0)

Expected output:

code

cherry
banana
apple

Thinking prompt: When would negative indexing be more useful than positive indexing? Hint: when you always want the last few items, regardless of list length.

2.4 Range of Indexes (Slicing)

You can grab a slice (a section) of a list using a colon : inside the brackets.

Syntax:

python

list_name[start : end]

start = the index to begin from (included)
end = the index to stop before (NOT included)

python

fruits = ["apple", "banana", "cherry", "orange", "kiwi", "melon", "mango"]
print(fruits[2:5])

Expected output:

code

['cherry', 'orange', 'kiwi']

Items at indexes 2, 3, and 4 are returned. Index 5 is the stopping point · it is NOT included.

Leaving out the start index · slice from the beginning:

python

fruits = ["apple", "banana", "cherry", "orange", "kiwi", "melon", "mango"]
print(fruits[:4])

Expected output:

code

['apple', 'banana', 'cherry', 'orange']

Leaving out the end index · slice to the end:

python

fruits = ["apple", "banana", "cherry", "orange", "kiwi", "melon", "mango"]
print(fruits[2:])

Expected output:

code

['cherry', 'orange', 'kiwi', 'melon', 'mango']

Negative index slicing:

python

fruits = ["apple", "banana", "cherry", "orange", "kiwi", "melon", "mango"]
print(fruits[-4:-1])

Expected output:

code

['orange', 'kiwi', 'melon']

2.5 Checking If an Item Exists · `in` Keyword

Use the in keyword to check whether a specific value is present in the list:

python

fruits = ["apple", "banana", "cherry"]

if "banana" in fruits:
    print("Yes, banana is in the list!")

Expected output:

code

Yes, banana is in the list!

python

if "mango" in fruits:
    print("Found mango")
else:
    print("mango is NOT in the list")

Expected output:

code

mango is NOT in the list

✏️ Your Task

Practise what you just learned about Accessing List Items. Open your editor, type the examples above by hand, modify them, and observe what changes.

Phase 5 of 9

Part 3 · Changing List Items

3.1 Why Would You Change a List Item?

Lists are mutable · meaning you can change their contents after creation. This is different from strings, which are immutable (once created, you cannot change individual characters).

Real-world example: A store's inventory changes daily. Items go in and out of stock. A list lets you update that data without rebuilding everything from scratch.

3.2 Changing One Item

Assign a new value directly to a specific index:

python

fruits = ["apple", "banana", "cherry"]
fruits[1] = "mango"
print(fruits)

Expected output:

code

['apple', 'mango', 'cherry']

Position 1 (which was "banana") is now "mango". The other items are unchanged.

3.3 Changing a Range of Items

You can replace several items at once using a slice:

python

fruits = ["apple", "banana", "cherry", "orange", "kiwi"]
fruits[1:3] = ["mango", "melon"]
print(fruits)

Expected output:

code

['apple', 'mango', 'melon', 'orange', 'kiwi']

Items at indexes 1 and 2 ("banana" and "cherry") were replaced with "mango" and "melon".

What if you replace a range with MORE items than the original range?

python

fruits = ["apple", "banana", "cherry"]
fruits[1:2] = ["mango", "melon", "grape"]
print(fruits)

Expected output:

code

['apple', 'mango', 'melon', 'grape', 'cherry']

Only index 1 ("banana") was in the slice, but it was replaced by THREE items. The list grew longer!

What if you replace a range with FEWER items?

python

fruits = ["apple", "banana", "cherry", "orange"]
fruits[1:3] = ["mango"]
print(fruits)

Expected output:

code

['apple', 'mango', 'orange']

"banana" and "cherry" (2 items) were replaced by only "mango" (1 item). The list shrank.

3.4 Inserting an Item Without Replacing · `insert()`

insert(index, value) adds a new item at a specific position without removing anything:

python

fruits = ["apple", "banana", "cherry"]
fruits.insert(2, "watermelon")
print(fruits)

Expected output:

code

['apple', 'banana', 'watermelon', 'cherry']

"watermelon" was inserted at position 2. "cherry" was pushed to position 3. Nothing was deleted.

✏️ Your Task

Practise what you just learned about Changing List Items. Open your editor, type the examples above by hand, modify them, and observe what changes.

Phase 6 of 9

Part 4 · Adding Items to a List

4.1 The Three Ways to Add Items

Method	What it does
`append(value)`	Adds one item to the end of the list
`insert(index, value)`	Adds one item at a specific position
`extend(iterable)`	Adds multiple items from another list (or any iterable) to the end

4.2 `append()` · Add to the End

python

fruits = ["apple", "banana", "cherry"]
fruits.append("orange")
print(fruits)

Expected output:

code

['apple', 'banana', 'cherry', 'orange']

append() is the most commonly used method for adding items. It always places the new item at the very end.

Second example · building a list step by step:

python

shopping = []
shopping.append("milk")
shopping.append("eggs")
shopping.append("bread")
print(shopping)

Expected output:

code

['milk', 'eggs', 'bread']

We started with an empty list [] and built it up one item at a time. This pattern is extremely common in real programs.

4.3 `insert()` · Add at a Specific Position

We already saw insert() in Part 3, but here it is as an add operation:

python

fruits = ["apple", "banana", "cherry"]
fruits.insert(1, "kiwi")
print(fruits)

Expected output:

code

['apple', 'kiwi', 'banana', 'cherry']

"kiwi" was inserted at position 1. Everything from position 1 onwards was shifted right by one.

Insert at the beginning (position 0):

python

fruits = ["apple", "banana", "cherry"]
fruits.insert(0, "strawberry")
print(fruits)

Expected output:

code

['strawberry', 'apple', 'banana', 'cherry']

4.4 `extend()` · Add Multiple Items from Another List

python

fruits = ["apple", "banana", "cherry"]
more_fruits = ["mango", "pineapple", "papaya"]
fruits.extend(more_fruits)
print(fruits)

Expected output:

code

['apple', 'banana', 'cherry', 'mango', 'pineapple', 'papaya']

Every item from more_fruits was added individually to the end of fruits.

extend() vs append() · the key difference:

python

fruits = ["apple", "banana"]

# append adds the whole list AS ONE item:
fruits.append(["mango", "kiwi"])
print(fruits)

Expected output:

code

['apple', 'banana', ['mango', 'kiwi']]

python

fruits = ["apple", "banana"]

# extend adds each item separately:
fruits.extend(["mango", "kiwi"])
print(fruits)

Expected output:

code

['apple', 'banana', 'mango', 'kiwi']

Common beginner mistake: Using append() when you meant extend(). The result is a nested list instead of a flat list.

extend() also works with other iterables like tuples:

python

fruits = ["apple", "banana", "cherry"]
fruits.extend(("kiwi", "orange"))
print(fruits)

Expected output:

code

['apple', 'banana', 'cherry', 'kiwi', 'orange']

✏️ Your Task

Practise what you just learned about Adding Items to a List. Open your editor, type the examples above by hand, modify them, and observe what changes.

Phase 7 of 9

Part 5 · Removing Items from a List

5.1 The Ways to Remove Items

Method / Keyword	What it does
`remove(value)`	Removes the first occurrence of a specific value
`pop(index)`	Removes the item at a specific index (default: last item)
`del list[index]`	Deletes item at a specific index, or deletes the whole list
`clear()`	Empties the list completely (list still exists, but has no items)

5.2 `remove()` · Remove by Value

python

fruits = ["apple", "banana", "cherry"]
fruits.remove("banana")
print(fruits)

Expected output:

code

['apple', 'cherry']

"banana" was found and removed. The list shrank by one.

What if the value appears more than once?

remove() only deletes the first occurrence:

python

fruits = ["apple", "banana", "cherry", "banana", "mango"]
fruits.remove("banana")
print(fruits)

Expected output:

code

['apple', 'cherry', 'banana', 'mango']

Only the first "banana" (at index 1) was removed. The second "banana" (originally at index 3) remains.

What if the value does not exist?

python

fruits = ["apple", "banana", "cherry"]
fruits.remove("mango")   # "mango" is not in the list

Expected output:

code

ValueError: list.remove(x): x not in list

Common beginner mistake: Calling remove() on a value that is not in the list. Always check first with in if you are unsure.

Safe version:

python

fruits = ["apple", "banana", "cherry"]
if "mango" in fruits:
    fruits.remove("mango")
else:
    print("mango was not found in the list")

Expected output:

code

mango was not found in the list

5.3 `pop()` · Remove by Index

pop() removes and returns the item at a given index. If no index is given, it removes the last item.

python

fruits = ["apple", "banana", "cherry"]
fruits.pop(1)
print(fruits)

Expected output:

code

['apple', 'cherry']

pop() without an index · removes the last item:

python

fruits = ["apple", "banana", "cherry"]
fruits.pop()
print(fruits)

Expected output:

code

['apple', 'banana']

pop() returns the removed item · you can store it:

python

fruits = ["apple", "banana", "cherry"]
removed = fruits.pop(1)
print("Removed:", removed)
print("List now:", fruits)

Expected output:

code

Removed: banana
List now: ['apple', 'cherry']

This is very useful when you want to process the item you are removing.

5.4 `del` · Delete by Index or Slice

The del keyword deletes an item at a specific index:

python

fruits = ["apple", "banana", "cherry"]
del fruits[0]
print(fruits)

Expected output:

code

['banana', 'cherry']

Delete a slice:

python

fruits = ["apple", "banana", "cherry", "orange", "kiwi"]
del fruits[1:3]
print(fruits)

Expected output:

code

['apple', 'orange', 'kiwi']

Delete the entire list variable:

python

fruits = ["apple", "banana", "cherry"]
del fruits
# print(fruits)   # This would now cause a NameError — the variable no longer exists

After del fruits, the variable fruits is completely gone from memory. This is different from clear().

5.5 `clear()` · Empty the List

clear() removes all items from the list, but the list variable itself still exists:

python

fruits = ["apple", "banana", "cherry"]
fruits.clear()
print(fruits)

Expected output:

code

[]

The list is now empty [], but fruits still exists as a variable. You can add new items to it later.

✏️ Your Task

Practise what you just learned about Removing Items from a List. Open your editor, type the examples above by hand, modify them, and observe what changes.

Phase 8 of 9

Part 6 · Guided Practice Exercises

🎯 Your Challenge

Exercise 1 · Class Register

Objective: Create and display a list of student names.

Scenario: You are a teacher building a digital class register.

Steps:

Create a list called students with five student names.
Print the full list.
Print just the first student.
Print just the last student using negative indexing.
Print the number of students using len().

Starter code:

✏️ Task

1. Print the temperature for Wednesday (index 2). 2. Print temperatures for Tuesday to Friday (use slicing). 3. The Saturday reading was wrong · it should be 20. Fix it. 4. Print the updated list. 5. Check whether the temperature 30 is in the list and print a message. Expected output: ` 25 [19, 25, 30, 28] [22, 19, 25, 30, 28, 20, 21] 30 degrees was recorded this week. ` ·

python

students = ["Alice", "Bob", "Charlie", "Diana", "Eve"]
# Your code below:

Expected output:

code

['Alice', 'Bob', 'Charlie', 'Diana', 'Eve']
Alice
Eve
5

Self-check questions:

What index does "Charlie" have?
What would students[-2] return?
What would students[1:4] return?

Exercise 2 · Shopping Cart

Objective: Practice adding and removing items from a list.

Scenario: You are building a simple shopping cart.

Steps:

Start with an empty list called cart.
Use append() to add: "milk", "eggs", "bread", "cheese".
Print the cart.
The customer changed their mind · remove "eggs" using remove().
Add "yoghurt" at position 1 using insert().
Print the final cart.
Print the total number of items.

Expected output:

code

['milk', 'eggs', 'bread', 'cheese']
['milk', 'yoghurt', 'bread', 'cheese']
4

Optional what-if challenge: What would happen if you used pop(0) instead of remove("eggs")?

Exercise 3 · Temperature Log

Objective: Practice slicing and modifying a list.

Scenario: A weather station recorded temperatures for a week (in °C).

python

temperatures = [22, 19, 25, 30, 28, 17, 21]
# Days:          Mon Tue Wed Thu  Fri  Sat Sun

Tasks:

Print the temperature for Wednesday (index 2).
Print temperatures for Tuesday to Friday (use slicing).
The Saturday reading was wrong · it should be 20. Fix it.
Print the updated list.
Check whether the temperature 30 is in the list and print a message.

Expected output:

code

25
[19, 25, 30, 28]
[22, 19, 25, 30, 28, 20, 21]
30 degrees was recorded this week.

Exercise 4 · Combining Two Inventories

Objective: Practice using extend().

Scenario: Two warehouses need to merge their stock lists.

python

warehouse_a = ["screws", "bolts", "nails"]
warehouse_b = ["hammers", "drills", "saws"]

Use extend() to merge warehouse_b into warehouse_a.
Print the combined list.
Use del to remove "bolts" by index.
Print the final list.

Expected output:

code

['screws', 'bolts', 'nails', 'hammers', 'drills', 'saws']
['screws', 'nails', 'hammers', 'drills', 'saws']

Phase 9 of 9

Part 8 · Common Beginner Mistakes (Summary)

Mistake 1 · IndexError: Index Out of Range

python

# WRONG
fruits = ["apple", "banana", "cherry"]
print(fruits[3])   # Only indexes 0, 1, 2 exist!

code

IndexError: list index out of range

Fix: Remember that a list of n items has indexes 0 to n-1. Use len(fruits) - 1 for the last valid index.

Mistake 2 · Confusing `append()` and `extend()`

python

# WRONG – adds nested list
fruits = ["apple", "banana"]
fruits.append(["cherry", "mango"])
print(fruits)   # ['apple', 'banana', ['cherry', 'mango']]

Fix: Use extend() when you want to add multiple items individually:

python

fruits = ["apple", "banana"]
fruits.extend(["cherry", "mango"])
print(fruits)   # ['apple', 'banana', 'cherry', 'mango']

Mistake 3 · `remove()` on a Non-Existent Value

python

# WRONG
fruits = ["apple", "banana"]
fruits.remove("grape")   # ValueError!

Fix: Check first with in:

python

if "grape" in fruits:
    fruits.remove("grape")

Mistake 4 · Forgetting That Slicing Does NOT Include the End Index

python

fruits = ["apple", "banana", "cherry", "orange"]
print(fruits[1:3])   # Returns items at index 1 AND 2 — NOT 3

code

['banana', 'cherry']

The slice [1:3] means "from index 1 up to but NOT including index 3".

Mistake 5 · `del` vs `clear()` vs Setting to `[]`

python

fruits = ["apple", "banana"]

# del removes the variable entirely
del fruits
# print(fruits)   # NameError — 'fruits' does not exist!

# clear() empties the list, but the variable still exists
fruits = ["apple", "banana"]
fruits.clear()
print(fruits)     # []  — variable exists, just empty

# Assigning [] replaces the list with a new empty one
fruits = ["apple", "banana"]
fruits = []
print(fruits)     # []

Mistake 6 · Modifying a List While Looping Over It

This is an advanced mistake to be aware of. Avoid removing items from a list inside a for loop that is iterating over the same list · it causes unexpected behaviour. Use a copy or a different approach.

✏️ Your Task

Practise what you just learned about Common Beginner Mistakes (Summary). Open your editor, type the examples above by hand, modify them, and observe what changes.

🏗️ Build It — Mini Project

Project Overview

You will build a Student Grade Tracker · a small Python program that stores student names and their exam scores, allows grade updates, adds new students, and removes students who have withdrawn.

This project uses every skill from today's lesson.

Stage 1 · Setup

Create two lists: one for student names, one for their scores. Each index position corresponds to the same student.

starter.py

# Stage 1 – Create the lists
names  = ["Alice", "Bob", "Charlie", "Diana", "Eve"]
scores = [88, 74, 91, 65, 83]

print("Students:", names)
print("Scores:  ", scores)
print("Total students:", len(names))

Lesson 07 complete! 🎉

You covered:

✅ Lesson Introduction
✅ Prerequisite Concepts
✅ Part 1 · What Is a Python List?
✅ Part 2 · Accessing List Items
✅ Part 3 · Changing List Items
✅ Part 4 · Adding Items to a List
✅ Part 5 · Removing Items from a List
✅ Part 6 · Guided Practice Exercises

← Lesson 06 Lesson 08 →

Python Lists: Create, Access, Change, Add & Remove

👋 Welcome to Lesson 07

1.1 The Real-World Analogy

1.2 The Technical Definition

1.3 Creating Your First List

1.4 How Many Items? · len()

1.5 Lists Can Hold Other Lists (Nested Lists)

1.6 The list() Constructor

1.7 List Data Type

2.1 What Is an Index?

2.2 Accessing a Single Item

2.3 Negative Indexing

2.4 Range of Indexes (Slicing)

2.5 Checking If an Item Exists · in Keyword

3.1 Why Would You Change a List Item?

3.2 Changing One Item

3.3 Changing a Range of Items

3.4 Inserting an Item Without Replacing · insert()

4.1 The Three Ways to Add Items

4.2 append() · Add to the End

4.3 insert() · Add at a Specific Position

4.4 extend() · Add Multiple Items from Another List

5.1 The Ways to Remove Items

5.2 remove() · Remove by Value

5.3 pop() · Remove by Index

5.4 del · Delete by Index or Slice

5.5 clear() · Empty the List

Exercise 1 · Class Register

Exercise 2 · Shopping Cart

Exercise 3 · Temperature Log

Exercise 4 · Combining Two Inventories

Mistake 1 · IndexError: Index Out of Range

Mistake 2 · Confusing append() and extend()

Mistake 3 · remove() on a Non-Existent Value

Mistake 4 · Forgetting That Slicing Does NOT Include the End Index

Mistake 5 · del vs clear() vs Setting to []

Mistake 6 · Modifying a List While Looping Over It

Project Overview

Stage 1 · Setup

Lesson 07 complete! 🎉

1.4 How Many Items? · `len()`

1.6 The `list()` Constructor

2.5 Checking If an Item Exists · `in` Keyword

3.4 Inserting an Item Without Replacing · `insert()`

4.2 `append()` · Add to the End

4.3 `insert()` · Add at a Specific Position

4.4 `extend()` · Add Multiple Items from Another List

5.2 `remove()` · Remove by Value

5.3 `pop()` · Remove by Index

5.4 `del` · Delete by Index or Slice

5.5 `clear()` · Empty the List

Mistake 2 · Confusing `append()` and `extend()`

Mistake 3 · `remove()` on a Non-Existent Value

Mistake 5 · `del` vs `clear()` vs Setting to `[]`