Python Academy · Lesson

Creating and Accessing Lists

Build lists and access elements by index and slice.

Lesson 1 of 414 steps

Creating and Accessing Lists is a free Python Academy lesson on CoddyKit. This is lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Python Academy learning path, and your progress syncs across the web and the CoddyKit app. The Python Academy course includes 4 lessons in total.

Introduction

Lists are Python's most flexible ordered collection. They hold any mix of types and support indexing, slicing, and iteration.

Creating a List

my_list = [1, 2, 3] or empty = [] Lists are ordered and mutable. Elements can be of any type.

nums = [1, 2, 3]
mixed = [1, 'hi', True]
print(nums, mixed)

Accessing Elements

nums[0] is 1, nums[-1] is the last element. Indexing works exactly like strings.

nums = [10, 20, 30]
print(nums[0], nums[-1])

Slicing Lists

nums[1:3] returns a new list with elements at index 1 and 2. nums[::-1] reverses the list.

nums = [1, 2, 3, 4, 5]
print(nums[1:3])
print(nums[::-1])

len() on Lists

len([1, 2, 3]) returns 3. Always valid even for empty lists.

print(len([1, 2, 3]))
print(len([]))

in Operator

3 in [1, 2, 3] returns True. in performs a linear search — O(n). For fast lookups use a set.

print(3 in [1, 2, 3])
print(9 in [1, 2, 3])

Iterating Over a List

for item in my_list: print(item) iterates in order. Use enumerate() to get index + value together.

fruits = ['apple', 'banana', 'cherry']
for i, f in enumerate(fruits):
    print(i, f)

Nested Lists

Lists can contain other lists: matrix = [[1,2],[3,4]]. Access with matrix[0][1] for row 0, column 1.

matrix = [[1, 2], [3, 4]]
print(matrix[0][1])

List from range()

list(range(5)) gives [0,1,2,3,4]. list(range(2,10,2)) gives [2,4,6,8].

print(list(range(5)))
print(list(range(2, 10, 2)))

Copying a List

copy = my_list[:] or copy = list(my_list). Do NOT do copy = my_list — that makes both names point to the same list.

a = [1, 2, 3]
b = a[:]  # proper copy
b.append(4)
print(a, b)

min(), max(), sum()

min([3,1,2]) is 1, max is 3, sum([1,2,3]) is 6. These work on any iterable of comparable values.

nums = [3, 1, 4, 1, 5]
print(min(nums), max(nums), sum(nums))

Quick Check

What does nums[::-1] return for nums = [1,2,3]?

Answer it in the interactive lesson

Recap

Lists are mutable, ordered sequences. Access by index, slice with [start:stop:step], iterate with for/enumerate. Always copy with [:] not =.

Keep Going

Great work! Move on to the next lesson to continue building your skills.

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Frequently Asked Questions

Is the “Creating and Accessing Lists” lesson free?

Yes — the full text of “Creating and Accessing Lists” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Python Academy course, upgrade to CoddyKit PRO. The Python Academy course includes 4 lessons in total.

What will I learn in “Creating and Accessing Lists”?

Build lists and access elements by index and slice. You practise Python Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Python Academy?

No prior experience is required. Python Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 4.

How long does the “Creating and Accessing Lists” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Python Academy lesson?

Yes. Every Python Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

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