Function Parameters: Positional and Keyword

Active learning helps students grasp function parameters because misunderstandings often arise when they only listen to explanations. When students test arguments directly, they see errors immediately and correct them through experience. This topic requires hands-on experimentation to build confidence in how positional and keyword arguments work together.

• Class 12
• Computer Science
• 4 activities
• 20 min–45 min

Learning Objectives

1. Compare the execution flow and output of Python functions when using only positional arguments versus only keyword arguments.
2. Design a Python function that accepts both positional and keyword arguments, demonstrating appropriate use cases for each.
3. Predict the output of function calls that mix positional and keyword arguments, identifying potential `TypeError` exceptions.
4. Analyze the readability and maintainability benefits of using keyword arguments in complex function definitions.

Collaborative Problem-Solving

⏱ 30 min·Pairs

Pair Programming: Argument Order Challenge

Pairs define a function with three positional parameters, like calculate_area(length, width, unit). They write calls using positional order, then swap to cause errors and fix with keywords. Discuss readability differences.

Prepare & details

Compare the use of positional arguments versus keyword arguments in function calls.

Facilitation Tip: During Pair Programming, circulate and listen for students explaining argument order explicitly so they verbalise the sequence rules.

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 45 min·Small Groups

Small Groups: Student Grade Calculator Design

Groups create a function with positional args for marks and keyword args for name, subject, scale='percentage'. Test mixed calls, add defaults, and share outputs. Rotate roles for coding and testing.

Prepare & details

Design a function that effectively utilizes both positional and keyword parameters.

Facilitation Tip: In Small Groups, provide a checklist of requirements so students focus on parameter design rather than formatting.

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 25 min·Whole Class

Whole Class: Output Prediction Relay

Project function definitions with mixed parameters. Teams predict outputs for 10 calls on slates, relay answers. Reveal with live execution and vote on common errors.

Prepare & details

Predict the output of function calls with mixed parameter types.

Facilitation Tip: For the Output Prediction Relay, give a 2-minute warning before discussion so students finalise predictions and justify choices.

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 20 min·Individual

Individual: Debug Worksheet

Provide buggy code snippets with incorrect positional/keyword mixes. Students identify errors, rewrite calls, and verify in Python. Collect for feedback.

Prepare & details

Compare the use of positional arguments versus keyword arguments in function calls.

Facilitation Tip: While students work on the Debug Worksheet, ask guiding questions like 'Why does this call fail? What would fix it?' instead of giving answers.

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Teaching This Topic

Teachers should start with concrete examples before abstract explanations, as students often confuse argument order with parameter names. Use live coding to demonstrate errors when arguments are swapped, then fix them together. Avoid rushing to keyword arguments before students master positional rules, as mixing too early can overwhelm them. Research shows that students retain parameter concepts better when they debug their own mistakes in pairs or small groups.

What to Expect

By the end of these activities, students will confidently distinguish between positional and keyword arguments, predict call outcomes accurately, and design functions that blend both methods effectively. They will also debug mixed calls without hesitation and explain their reasoning clearly.

Watch Out for These Misconceptions

Common Misconception

During Pair Programming: Argument Order Challenge, watch for students assuming any order works for positional arguments.

What to Teach Instead

Ask each pair to intentionally swap two positional arguments and run the function. The immediate TypeError will help them see that order matters strictly.

Common Misconception

During Small Groups: Student Grade Calculator Design, watch for students placing keyword arguments before positional ones in their function calls.

What to Teach Instead

Have groups share their function calls on the board and mark the positions of positional versus keyword arguments. Discuss why one style fails and the other succeeds.

Common Misconception

During Output Prediction Relay, watch for students believing keyword arguments override positional ones when names match.

What to Teach Instead

Use a function with duplicate parameter names in the relay questions. Students will see Python raises an error, reinforcing that names must be unique.

Assessment Ideas

Quick Check

After Pair Programming: Argument Order Challenge, collect each pair's two corrected function calls and their reasoning notes. Check for correct sequence and explicit order rules in their explanations.

Exit Ticket

During Small Groups: Student Grade Calculator Design, collect each group's final function and two example calls. Assess how they combined positional and keyword arguments and whether they used defaults correctly.

Discussion Prompt

After Output Prediction Relay, ask students to write one sentence explaining when they would prefer keyword arguments for simple functions. Use their responses to identify students who grasp readability benefits versus those still relying only on positional calls.

Extensions & Scaffolding

• Challenge students to write a function with three parameters where one is mandatory, one has a default, and one must use a keyword argument during the call.
• Scaffolding: Provide a partially completed function call with blanks for students to fill, showing where positional and keyword arguments fit.
• Deeper exploration: Ask students to compare performance differences between positional and keyword calls in loops, researching how Python handles each internally.

Key Vocabulary

Positional Argument	An argument passed to a function that is assigned to a parameter based on its position in the function call, matching the order in the function definition.
Keyword Argument	An argument passed to a function where the argument name is explicitly stated, allowing for flexible ordering and improved readability.
Function Signature	The combination of a function's name and the number and types of its parameters, defining how the function can be called.
Default Parameter Value	A value assigned to a parameter in the function definition that is used if no argument is provided for that parameter during the function call.