show x positionread the movement value
Lesson / Scratch & Game Design
What Is the Bug Trying to Tell You?
The game fails only when the player reaches safety while being caught near the right edge. Random edits have made it stranger. Reproduce the fault, inspect the game state, and test one possible cause.
Lesson plan
Reproduce the fault
Record the shortest sequence that produces the wrong ending.
Expose the state
Display a relevant coordinate or game-state value.
Test one explanation
Choose one possible cause and make a controlled test.
Repair and retest
Make the smallest useful change, then repeat the original sequence.
Give the bug report
Show the fault, the evidence, the repair, and a regression test.
Learning goals
- Describe the expected and observed results separately.
- Reproduce a bug with a short sequence of actions.
- Inspect a relevant value or state.
- Choose one possible cause.
- Run a controlled test and explain the evidence.
Small examples
say game_statemake the hidden mode visible
disable one scripttest a smaller system
repeat the same inputscheck that the fault is reproducible
Guided project
Escape from the Giant Pigeon
Reach the shelter before a huge pigeon catches you. Under the absurd premise is a precise system of coordinates, collision checks, and two possible endings.
Keyboard movement in four directions, Known starting positions, A pursuing pigeon, One or more safe areas.
Scratch, Coordinates, Movement, Collision, Game State.
A working version with a tested change, one repaired problem, and a clear explanation.
Teacher checkpoints
- 1The student describes the fault without guessing at its cause.
- 2A repeatable sequence triggers it.
- 3At least one relevant value is inspected.
- 4Only one hypothesis is tested at a time.
- 5The repair is explained from the evidence.
Common mistakes
- Several scripts are changed before the next test.
- Only the easiest successful path is tried.
- A delay hides a state problem for a moment.
- Testing stops after the symptom disappears once.
Optional challenges
Builder
- Create a bug report with exact steps.
Inventor
- Add temporary on-screen state monitors.
Boss Level
- Design an automated edge-case test sequence.
End-of-class demonstration
- What should happen?
- What actually happens?
- How can you reproduce it?
- What evidence did you inspect?
- Why did the fix work?