Technologies · Foundation · Creating with Code · Term 3

Debugging Our Programs: Finding and Fixing

Developing strategies to identify and correct errors (bugs) in simple block-based programs.

• ACARA Content Descriptions
• AC9TDEFP04

About This Topic

Debugging means finding and fixing errors in block-based programs, a core skill in the Australian Curriculum Technologies strand for Foundation students (AC9TDEFP04). Young learners explore simple programs using tools like ScratchJr or Code-a-Pillar, identifying issues such as blocks in the wrong order, missing repeat loops, or sprites moving unexpectedly. This builds early computational thinking and connects to the unit's focus on creating with code.

Students analyze common error types: connection problems where blocks do not snap correctly, logic flaws that change program outcomes, and sequence errors that halt execution. They construct step-by-step debug plans, like predicting what should happen, running tests with different inputs, and checking one change at a time. Justifying systematic testing shows how it saves time compared to random guesses.

These practices foster resilience and precision in problem-solving. Active learning benefits this topic most because students physically rearrange blocks, run programs immediately, and discuss fixes with peers, turning abstract errors into concrete, shareable experiences that stick.

Key Questions

1. Analyze common types of errors in block-based coding.
2. Construct a plan to debug a given program with an error.
3. Justify the importance of systematic testing in finding bugs.

Learning Objectives

• Identify common types of errors in block-based programs, such as incorrect block order or missing blocks.
• Construct a step-by-step plan to locate and fix a bug in a simple block-based program.
• Demonstrate the process of testing a program systematically to find errors.
• Explain why systematic testing is more effective than random guessing for debugging.

Before You Start

Sequencing Instructions

Why: Students need to understand how to arrange blocks in a logical order before they can identify when the sequence is incorrect.

Basic Block-Based Programming

Why: Familiarity with the interface and basic functions of a block-based coding tool is necessary to create and modify programs.

Key Vocabulary

bug	An error or mistake in a computer program that causes it to behave unexpectedly or incorrectly.
debugging	The process of finding and fixing errors (bugs) in a computer program.
sequence	The order in which instructions or blocks in a program are executed.
logic error	An error in the program's instructions that causes it to produce an incorrect result, even if it runs without stopping.
testing	Running a program to check if it works as expected and to find any errors.

Watch Out for These Misconceptions

Common Misconception

Bugs only happen to beginners who make mistakes.

What to Teach Instead

All programmers debug, even experts. Active prediction activities, where students guess outcomes before running code, help them see errors as part of iteration. Peer shares during pair work normalize debugging as routine.

Common Misconception

Fix bugs by adding more blocks randomly.

What to Teach Instead

Random changes often create new errors. Teaching checklists in small group stations guides systematic fixes, showing one change at a time. This builds planning skills through hands-on trials.

Common Misconception

One test run proves the program works.

What to Teach Instead

Programs need multiple inputs to catch logic bugs. Relay activities with varied tests reveal this, as class data shows patterns. Discussions help students justify broader testing.

Active Learning Ideas

Pair Debug Swap: Fix Partner's Code

Students create a simple program with one intentional bug, then swap with a partner. Partners predict the outcome, run it, note the error using a checklist, and fix it step by step. Pairs test the corrected version together and explain their process.

25 min·Pairs

Stations Rotation: Error Type Hunts

Set up three stations, each with a program showing one error type (sequence, logic, connection). Small groups visit each, run the code, describe the bug, and fix it on paper first. Rotate every 10 minutes and share fixes as a class.

40 min·Small Groups

Testing Relay: Systematic Checks

Whole class lines up with a shared buggy program projected. Each student tests one input, notes if it matches expected output, and passes to the next. Discuss patterns in results before fixing as a group.

30 min·Whole Class

Debug Plan Builder: Individual Practice

Give students a buggy program printout. They draw their debug plan: predict, test ideas, fix steps. Then code it digitally and verify. Share one plan with the class.

20 min·Individual

Real-World Connections

• Software developers at companies like Google use debugging techniques daily to find and fix errors in apps and websites, ensuring they function smoothly for millions of users.
• Video game designers meticulously debug their games to eliminate glitches and ensure a fun, consistent player experience before release.
• Robotics engineers debug the code controlling robots in factories, like those assembling cars, to ensure precision and safety in their movements.

Assessment Ideas

Quick Check

Present students with a short, intentionally buggy block-based program (e.g., a character that doesn't move correctly). Ask them to point to the block they think is causing the problem and explain why.

Discussion Prompt

Ask students: 'Imagine your program is supposed to make a cat meow twice, but it only meows once. What are three steps you would take to figure out why?' Record their ideas on the board.

Exit Ticket

Give students a simple program with a clear error. Ask them to write down one bug they found and one change they made to fix it. They can also draw a picture of the program working correctly.

Frequently Asked Questions

What are effective debugging strategies for Foundation block coding?

Use a three-step plan: predict what the code should do, run it and compare to prediction, change one thing and retest. Checklists for error types (sequence, logic, connection) guide beginners. Practice with simple loops and sprites builds confidence quickly. Link to AC9TDEFP04 by emphasizing systematic testing over trial and error.

How does debugging align with AC9TDEFP04?

AC9TDEFP04 requires developing strategies to identify and correct errors in programs. Lessons cover analyzing bugs, planning fixes, and justifying testing, directly matching the standard. This prepares students for creating reliable digital solutions in later years.

How can active learning help students master debugging?

Active approaches like pair swaps and station rotations let students manipulate blocks hands-on, run code live, and explain errors aloud. This immediate feedback loop clarifies cause and effect, while collaboration exposes diverse fix ideas. Compared to watching demos, it boosts retention and problem-solving persistence by 30-50% in early coding studies.

Why emphasize systematic testing in block-based programs?

Systematic testing catches hidden logic errors that single runs miss, teaching efficiency. Students learn programs must handle varied inputs, like different sprite paths. Relay games make this fun and collective, reinforcing that planned checks prevent endless tweaking.