Python Block Structure and Indentation - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

What will Python raise if the print line is not indented inside the function?

Python

def greet():
print("Hello")
# Python raises: [1]

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AIndentationError

BSyntaxError

CNameError

DTypeError

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing IndentationError with SyntaxError — IndentationError is a subclass of SyntaxError but more specific.

Thinking missing indentation causes a runtime error instead of a parse-time error.

Python raises IndentationError when a statement that should be inside a block is not indented. The print must be indented under def.

2fill in blank

medium

How many spaces does Python's PEP 8 standard recommend per indentation level?

Python

# PEP 8 recommends [1] spaces per indent level
def example():
    if True:
        pass  # this line is 2 levels deep

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A2

B4

C8

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 2 spaces — common in other languages but not Python's standard.

Mixing tabs and spaces which causes IndentationError.

Python's PEP 8 style guide recommends 4 spaces per indentation level. The pass line is 2 levels deep so it uses 8 spaces total (2 × 4).

3fill in blank

hard

What does this code print? Pay close attention to which print belongs inside the loop.

Python

for i in range(3):
    print("A")
print("B")
# Total lines printed: [1]

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A3

B1

C6

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking both prints are inside the loop — only the indented one is.

Forgetting that the unindented print runs once after the loop.

The indented print("A") runs 3 times inside the loop. The unindented print("B") runs once after the loop ends. Total output: 4 lines (A, A, A, B).

4fill in blank

hard

Fill both blanks. The return statement's indentation decides when the function returns.

Python

def add_until(n):
    total = 0
    for i in range(1, n+1):
        total += i
    return total

print(add_until(3))
# Output: [1]
# return belongs to the [2] block

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A6

B1

Cfunction

Dloop

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking return is inside the loop — check its indentation level.

Confusing function-level and loop-level indentation.

The return is at the function level (one indent), not inside the loop. So the loop completes fully (1+2+3=6) before returning. If return were indented inside the loop, it would return 1 on the first iteration.

5fill in blank

hard

Fill all three blanks. Determine each output line based on which block each print belongs to.

Python

x = 10
if x > 5:
    print("big")
    if x > 8:
        print("very big")
print("done")
# Line 1: [1]
# Line 2: [2]
# Line 3: [3]

Drag options to blanks, or click blank then click option'

Abig

Bvery big

Cdone

Dnothing

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking 'done' only prints when conditions are true — it is outside all if blocks.

Missing the nested if block — the second indent level creates a block inside a block.

Since x=10: the outer if x > 5 is true → prints big. The nested if x > 8 is also true → prints very big. The unindented print("done") always runs because it is outside all if blocks.