Python Programming For Beginners

Key ConceptsThis chapter covers how Python runs your code, focusing on correct syntax and indentation. For exams, most marks are lost because of tiny formatting issues (especially indentation) or missing punctuation.

Python executes line by line: each statement is parsed first, then executed in order.

Syntax must be exact: missing brackets/quotes or wrong punctuation causes a SyntaxError before execution.

Indentation defines code blocks: Python uses indentation (not braces) to group statements.

Indentation must be consistent: mix of tabs/spaces or uneven levels can cause IndentationError or logic mistakes.

Basic statements follow clear patterns:

print("text") outputs text

name = value assigns a value

if condition: starts a block that must be indented

Errors happen at different times:

Syntax/indent problems fail at parse time

Logic issues run but produce wrong results

Before you continue: Can you explain what indentation means for an if statement in Python?

Key TermsSyntax - the exact structure Python expects (punctuation, brackets, quotes).

Indentation - the whitespace at the start of a line that groups statements into blocks.

Block - a group of statements controlled by a header line (e.g., if ...:).

Parse time - when Python reads your code and checks grammar before running it.

SyntaxError - error raised when code grammar is incorrect.

IndentationError - error raised when indentation is missing/incorrect for a block.

Statement - a single line instruction Python can execute (e.g., print(...), x = 3).

Active RecallSyntax: __________

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Indentation: __________

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Block: __________

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Parse time: __________

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SyntaxError: __________

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IndentationError: __________

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Statement: __________

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Worked ExamplesExample 1: Basic print and assignmentWrite a valid statement: name = "Ada"

Output it with a correct syntax call: print(name)

Python runs in order: assignment first, then printing.

Now you try:

Write two lines to assign x = 5 and print x.

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Example 2: If-statement indentationUse a header with a colon: if x > 0:

Indent the statements that belong to the block (same indentation level).

Do not indent lines that should run outside the block.

Now you try:

Write code that prints "positive" only when n > 0.

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Example 3: Detecting indentation mistakesConsider this pattern (wrong):

Header ends with :

Next line is not indented

Python treats the block as missing → IndentationError (or similar).

Fix by indenting the block consistently.

Now you try:

Identify the indentation rule: after if flag: the next line must be ____.

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Practice Questions(4-mark) Describe what Python uses indentation for, and why if condition: needs the following lines indented.

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(4-mark) Give one example of a SyntaxError cause (e.g., missing bracket/quote) and state what happens when it occurs.

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(8-mark) Explain the difference between SyntaxError and IndentationError, including when each is detected (parse time vs block formatting).

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