Before diving into the detailed point‐by‐point criteria, here’s a high‐level summary of the FRQ 1 rubric for the 2024 AP Computer Science A exam:

• Total points: 9 points (Part (a): 4 points; Part (b): 5 points) (AP Central)
• Question focus: Methods and control structures involving simulation methods (simulateOneDay, simulateManyDays) (AP Central)
• Scoring approach: Award points based on the presence and correctness of key algorithmic and structural elements; penalties (up to 3 per question) are applied only after points are earned (AP Central)

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Overview of Scoring Criteria

The rubric is divided into two parts corresponding to the two methods students implement. For each part:

1. Point‐by‐point criteria specify exactly what feature or behavior must be in the student’s code to earn the point. (AP Central)
2. Decision rules clarify allowable variations (e.g., off‐by‐one in comparisons, reversed comparison operators) and disallowed errors. (AP Central)

No part may receive negative credit; penalty points (such as array‐access confusion or extraneous side‐effects) are only deducted in subparts that have already earned credit, with a maximum of 3 penalty points per question. (AP Central)

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Part (a): simulateOneDay (4 points)

Point	Criterion
1	Random value generation: At least one call to Math.random() to generate a random value.
2	5% probability branch: Use a comparison of the random value against a constant to create a 5% case.
3	Random integer [10, 50]: Cast and scale a random value to produce an integer uniformly in [10, 50].
4	Food‐consumption logic: Multiply by numBirds, compare to currentFood, and subtract correctly in both cases.

1. Random value generation (1 point):

• Student must call Math.random() at least once. (AP Central)
• Even if they fail to use the generated value, the point can be earned; incorrect calls or omission of Math.random() disqualify. (AP Central)

2. 5% probability branch (1 point):

• Code must implement two cases based on the random value (e.g., if (condition < 0.05) … else …). (AP Central)
• Variations (using <=, reversing 5%/95%, or slight casting differences) are acceptable provided the probability is correctly split. (AP Central)

3. Random integer [10, 50] (1 point):

• Student must generate an integer in [10, 50], typically via (int)(Math.random()*41) + 10. (AP Central)
• Off‐by‐one casting or incorrect call of Math.random disqualifies. (AP Central)

4. Food‐consumption logic (1 point):

• Code must compute totalEaten = numBirds * eachBirdEats, compare with currentFood, and update currentFood correctly in all cases. (AP Central)
• Acceptable even if comparisons use <=/>=, but reversing branches or allowing negative currentFood invalidates. (AP Central)

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Part (b): simulateManyDays (5 points)

Point	Criterion
5	Call simulateOneDay: At least one correct invocation with the numBirds parameter.
6	Loop guard: Loop (e.g., for or while) runs at most numDays times and checks currentFood > 0.
7	Day‐count algorithm: Correctly count the number of days simulated while food remains.
8	Food‐availability check: Compare currentFood to 0 within loop to determine continuation.
9	Return value: Return an int in all cases (either days simulated or numDays).

5. Call simulateOneDay (1 point):

• Must invoke simulateOneDay(numBirds) within the loop. (AP Central)
• Incorrect calls or calls on another object/class lose the point. (AP Central)

6. Loop guard (1 point):

• Loop must iterate no more than numDays times and guard against currentFood == 0. (AP Central)
• Variations in loop construct are allowed if logically equivalent. (AP Central)

7. Day‐count algorithm (1 point):

• Code must initialize and update a counter for days where food was available. (AP Central)
• Extra iterations are permissible if counter remains correct; failure to test or initialize counter loses credit. (AP Central)

8. Food‐availability check (1 point):

• Must compare currentFood to 0 inside loop to decide whether to continue simulation. (AP Central)
• Off‐by‐one in loop context is acceptable as long as comparison exists. (AP Central)

9. Return value (1 point):

• Must return an int (either the count or numDays). (AP Central)
• Returning a constant is acceptable if type correct. (AP Central)

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Penalties and Common Errors

A maximum of 3 penalty points may be assessed per question, only in parts that have earned credit. Common 1-point penalties:

• Array/collection access confusion (e.g., using [] vs. get()) (AP Central)
• Extraneous side-effect code (e.g., printing, incorrect precondition) (AP Central)
• Undeclared local variables (using variables without declaration) (AP Central)
• Destruction of persistent data (modifying parameter references) (AP Central)
• Void method returning a value (AP Central)

No Penalty for minor issues with no side‐effects, such as:

• Case/spelling discrepancies when unambiguous (AP Central)
• Use of private/public qualifier on local variables (AP Central)
• Missing semicolons or braces when intent is clear (AP Central)

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This rubric aligns precisely with the official 2024 College Board scoring guidelines for AP Computer Science A FRQ 1, ensuring transparent and fair grading.