Change the quiz

Your goal is to change a question and explain how a button changes program state.

Use the default quiz, or copy quiz Main and the shared ScoreDisplay using the switching steps.

Before running, predict the feedback and score after entering 41, then 42, then trying to click Check answer again. Run and compare your prediction. The original question awards 10 points once; the button becomes disabled after a correct answer. A wrong answer lets you try again.

Find points, answer, feedback, check and score. Which hold values and which refer to objects? Find where setup() creates the controls and where checkAnswer() changes them.

check.setOnAction(event -> checkAnswer());

Read this as “when this button is clicked, call checkAnswer.” You can use this line without learning all lambda syntax today. setup() builds the interface once; SimpleApp has no repeated draw() loop. Main owns the score; calling score.setScore(points) updates the displayed number.

1. Change the question to “What is 8 + 5?” and the expected answer to "13". Keep the answer in quotes because a TextField supplies text.
2. Award 5 points instead of 10. Keep the correct-answer button lock.
3. Replace “Try again.” with helpful feedback that does not reveal the answer. Then change either the window title or the VBox spacing.

Save, Stop and Run App after each change. As a debugging exercise, remove the semicolon from points += 5;, try Run App, use Problems to find the source line, then restore the semicolon and rerun. The compiler location can point just after the actual mistake. Keep the repaired program.

Action	Expected result
Enter a blank answer or 12	Your feedback appears; score stays 0; retry remains available
Enter 13	Correct feedback; score becomes 5; Check answer is disabled
Try to check again after success	Score stays 5
Stop and run again	Score begins at 0 and checking is enabled

trim() removes surrounding spaces; equals("13") compares string content. Do not replace it with == for this text comparison.

Show your working question. Explain which method runs at startup, which runs after a click, and why the score is not awarded twice. Include your repaired compile error and two actual check results in your lesson record.

Optional: add a hint Label to the VBox in setup(). It should help someone think, and the scoring and retry rules should still pass the checks above.