JSS 2 Second Term

Lesson objectives

By the end of the week, learners should be able to:

1. Identify common syntax errors such as missing LET or misspelled variable.
2. Fix a deliberately broken BASIC program step by step.
3. Run a corrected program and confirm the expected output.
4. Describe how an interpreter reports an error to the user.
5. State why debugging builds careful habits in programming.

Key vocabulary

• Debugging: finding and fixing mistakes in a program.
• Syntax error: a mistake in the rules of the programming language.
• Misspelling: a wrong letter in a keyword or identifier.
• Runnable program: a program that executes without fatal errors.
• Error message: the text the interpreter prints when it finds a problem.
• Habit: a repeated practice that becomes automatic with effort.
• Careful habit: a deliberate attention to detail that prevents repeats.

Common misconceptions

• "Broken programs are useless." Debugging turns broken programs into working ones.
• "Errors mean the program is broken forever." Errors are signals the developer can use to improve the code.
• "Fixing one bug fixes all bugs." Each bug needs its own targeted fix.

Teacher activities

1. Starter: show a deliberately broken program and display the error message.
2. Explain the common syntax errors and model one fix step by step.
3. Run the corrected program and confirm the output matches expectations.
4. Describe how the interpreter reports the original error.
5. Give learners a broken program and walk pairs through the debugging cycle.
6. Close with the exit question about why debugging matters for programmers.

Student activities

1. Observe the starter broken program and read the error message.
2. Identify the first syntax error and propose the fix.
3. Fix the program and run it to check the output.
4. Explain how the interpreter told you the program was broken.
5. Walk a partner through the debugging cycle step by step.
6. Answer the exit question in one sentence about the value of debugging.

Practical / learning evidence

A fixed BASIC program with both the original broken version and the corrected version, plus the confirmed output. Submit both the broken and corrected versions for marking.

Resources and preparation

Computers with the interpreter, blank source windows and a broken-program template. Keep a backup copy of the broken version somewhere learners cannot overwrite it. Disable Caps Lock before typing.

Assessment for learning

Inspect the broken version for visible errors and the corrected version for matching output. Check the correction is specific and explains each fix. Ask a learner to describe how the error message pointed to the location of the problem.

Inclusion and homework

Prebuild the interpreter and broken program in a read-only folder for learners lacking install capability. Provide a two-line-code-per-day debugging template. Extend confident learners with three broken segments and a blind debugging challenge. Homework: find one hidden syntax error in a sample program and write the correction.