Functions and Procedures: Modular Code

Active learning works well for teaching functions and procedures because students need to see modularity in action to grasp its benefits. When learners build and call their own reusable blocks, they experience firsthand how organization improves efficiency and clarity in code.

• Foundation
• Technologies
• 4 activities
• 25 min–45 min

Learning Objectives

1. Create a simple program using ScratchJr that defines and calls a custom function to perform a sequence of actions.
2. Compare the length and readability of a program written with repeated code versus one using a defined function.
3. Explain how defining a function helps to organize a program into smaller, manageable parts.
4. Justify when it is more efficient to create a new function instead of writing sequential code for a task.

Experiential Learning

⏱ 30 min·Pairs

Pair Build: Reusable Dance Function

In pairs, students create a function block with three dance moves like spin, jump, and wave. They call the function four times in a program, adding sounds each time. Partners switch roles to test and tweak for smoother playback.

Prepare & details

Construct a program that utilizes functions to break down complex tasks into smaller parts.

Facilitation Tip: During Pair Build, circulate and ask pairs to count the total blocks in their programs before and after using functions to highlight the difference in code length.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 45 min·Small Groups

Small Group Challenge: Story Action Modules

Groups define two procedures, such as 'hide behind tree' and 'run to friend,' for a simple adventure story. They sequence calls to build the full narrative, then swap one procedure with another's for a remix. Record observations on efficiency.

Prepare & details

Analyze the benefits of using functions for code reusability and readability.

Facilitation Tip: For the Small Group Challenge, provide a checklist that includes defining modules, testing them, and remixing a peer’s project to emphasize iterative improvement.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 40 min·Whole Class

Whole Class Gallery: Function Share-Out

Each pair creates one unique function for animal behaviors, like 'swim across pond.' Project all on the board for the class to drag into new programs. Discuss which combinations work best and why.

Prepare & details

Justify when to create a new function versus writing sequential code.

Facilitation Tip: In the Whole Class Gallery, invite students to present their functions and explain why they chose to modularize specific actions in their stories.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 25 min·Individual

Individual Debug: Fix the Modular Maze

Students receive a maze program with broken function calls. They identify the issue, recreate the 'turn corner' procedure correctly, and test runs. Note before-and-after step counts.

Prepare & details

Construct a program that utilizes functions to break down complex tasks into smaller parts.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Teaching This Topic

Approach this topic by having students build small, meaningful functions that solve real problems in their programs. Avoid starting with abstract definitions of functions; instead, let students discover their purpose through repeated use. Teachers should model tracing function calls step by step to prevent the misconception that functions run automatically.

What to Expect

Successful learning shows when students can define a function, call it multiple times, and explain why modular code is useful. They should also compare modular and sequential code, identifying differences in length and readability.

Watch Out for These Misconceptions

Common Misconception

During Pair Build, watch for students who believe functions are only useful for long programs.

What to Teach Instead

Have students count the blocks in their sequential and modular versions, then ask them to justify why modularity helps even in short programs.

Common Misconception

During Whole Class Gallery, listen for explanations that suggest functions run all code at once.

What to Teach Instead

Ask students to trace the order of blocks step by step when calling a function, using visual cues like pointing to the screen to reinforce sequential execution.

Common Misconception

During Small Group Challenge, notice if students assume functions work without testing.

What to Teach Instead

Challenge groups to intentionally break their functions by changing a value, then fix the errors through peer review, emphasizing that functions require testing like any other code.

Assessment Ideas

Exit Ticket

After the Pair Build activity, ask students to draw or describe how they used a function to create a dance sequence and write one sentence explaining why using a function helped them.

Quick Check

During the Small Group Challenge, observe students as they define and call their functions. Ask them to point out the function definition and its call site, noting which students can identify and explain these parts.

Discussion Prompt

After the Whole Class Gallery, present two versions of a simple animation: one with repeated blocks for a character’s dance, and one using a 'dance move' function. Ask students which program is shorter and which is easier to understand, and have them explain their reasoning in pairs before sharing with the class.

Extensions & Scaffolding

• Challenge students who finish early to create a function that combines sound and motion, then call it in three different parts of their program.
• For students who struggle, provide pre-written function blocks with blanks to fill in, so they focus on calling the function rather than writing its definition.
• Deeper exploration: Ask students to compare their modular program with a peer’s sequential version and write a short reflection on which they would prefer to debug and why.

Key Vocabulary

Function	A named set of instructions that performs a specific task. It can be used multiple times in a program.
Procedure	Another name for a function, especially when it is a set of steps to follow. In block-based coding, this is often how functions are referred to.
Call	To use or run a function that has already been defined. You 'call' the function by its name.
Modular Code	Code that is broken down into smaller, independent parts or modules (like functions), making it easier to manage and reuse.