AP Computer Science Principles (APCSP) Exam
Practice Questions With Answers and Explanations
Question 1. Which statement about citizen science is most accurate?
A. Volunteer data is always unbiased because contributors are not paid.
B. Computing can let volunteers contribute observations or processing effort to scientific projects at
large scale.
C. Only professional scientists are allowed to contribute data to any scientific computing project.
D. Citizen science eliminates the need to validate measurements or methods.
Correct Answer: B. Computing can let volunteers contribute observations or processing effort
to scientific projects at large scale.
Explanation: The correct statement accurately describes citizen science. Distributed participation can expand
data collection and analysis while still requiring protocols, validation, and awareness of sampling limitations.
The distractors rely on absolute claims that ignore stakeholders, context, or known security and privacy
limitations. APCSP impact questions reward careful evaluation rather than assuming that computing is
automatically beneficial, neutral, or perfectly secure.
Question 2. Which statement best describes Internet Protocol and routing?
A. Routing requires the sender to know the exact sequence of every router before transmission begins.
B. An IP address guarantees that every packet follows a single permanent route.
C. Routers use destination addressing information to forward packets toward their destinations across
interconnected networks.
D. Routers inspect the meaning of every application message and rewrite it before forwarding.
Correct Answer: C. Routers use destination addressing information to forward packets toward
their destinations across interconnected networks.
Explanation: The correct choice gives the standard networking or computing meaning of Internet Protocol and
routing. Internet routing forwards packets hop by hop using addressing and routing information rather than a
preselected permanent path. The distractors confuse the concept with a different network property or make
an absolute guarantee that protocols cannot provide. APCSP systems questions emphasize how layered,
interoperable systems behave rather than assuming perfect networks.
Question 3. A developer argues that malware does not need to be considered because
the program works as specified. Which response is best?
A. The issue matters only if the program produces a syntax error.
B. The developer is correct because working code cannot create social, ethical, privacy, or security
concerns.
C. Technical correctness is not enough; malicious software is defined by harmful or unauthorized
behavior, not by device type or how the file first reached the system.
D. The developer is correct as long as the program has more than one user.
Correct Answer: C. Technical correctness is not enough; malicious software is defined by
harmful or unauthorized behavior, not by device type or how the file first reached the system.
Explanation: The best response explains that malicious software is defined by harmful or unauthorized
behavior, not by device type or how the file first reached the system. A program can execute exactly as
designed and still create harmful, unfair, insecure, or privacy-sensitive outcomes. The distractors confuse
technical correctness with responsible impact assessment. APCSP explicitly treats the effects of computing as
broader than whether code compiles and runs.
Page 1
,Question 4. A group is developing a tool that summarizes survey responses. The team
is reviewing its workflow. Which practice should be changed first because it conflicts
with collaboration?
A. Use clear task ownership, shared conventions, and regular communication when multiple people
develop a program.
B. Have every team member independently rewrite the entire program and combine the files at the end.
C. Avoid documenting interfaces because collaborators should infer how every component works.
D. Allow each collaborator to change shared code without communicating what was changed.
Correct Answer: D. Allow each collaborator to change shared code without communicating
what was changed.
Explanation: The practice that conflicts most directly with collaboration is the one that says to allow each
collaborator to change shared code without communicating what was changed. Collaboration is more effective
when contributors coordinate responsibilities, interfaces, version changes, and design decisions. The correct
workflow should make progress easier to evaluate and should reduce avoidable uncertainty. Identifying the
conflicting practice requires comparing each choice with the core purpose of the development principle.
Question 5. Consider the following code segment. What value is displayed when the
segment finishes?
x ← 5
y ← 6
x ← x + y
y ← x - 4
z ← 2 * y - x
DISPLAY(z)
A. 7
B. 3
C. 11
D. 2
Correct Answer: B. 3
Explanation: The code first changes x from 5 to 11. It then sets y to 7 because the updated value of x is used
in the assignment. Therefore z becomes 2 × 7 − 11 = 3. The key is to use each variable's most recently
assigned value when tracing later statements.
Question 6. A developer claims that debugging is unnecessary when a program is small.
Which response is most accurate?
A. The practice should be postponed until the program has been used for at least one year.
B. The practice matters only when the program will be sold commercially.
C. Even a small program can benefit because systematic debugging isolates causes and verifies
corrections rather than relying on random changes.
D. Small programs cannot contain logic errors, so the practice is useful only for large systems.
Correct Answer: C. Even a small program can benefit because systematic debugging isolates
causes and verifies corrections rather than relying on random changes.
Explanation: The claim is incorrect because systematic debugging isolates causes and verifies corrections
rather than relying on random changes. Program size can affect how much process is needed, but it does not
eliminate the underlying value of the practice. The distractors make unsupported absolute claims about size,
commercial use, or timing. APCSP emphasizes general development principles that apply at different scales.
Page 2
,Question 7. Which change would most directly help a programmer use algorithmic
efficiency correctly?
A. Adopt this rule instead: Algorithms that produce the same output always require the same number of
steps.
B. Adopt this rule instead: Efficiency matters only when a program contains no procedures.
C. Choose the implementation that reflects this principle: Two algorithms that solve the same problem
can require very different amounts of time as input size grows.
D. Adopt this rule instead: An algorithm that is fastest for one small input is guaranteed to scale best for
all larger inputs.
Correct Answer: C. Choose the implementation that reflects this principle: Two algorithms that
solve the same problem can require very different amounts of time as input size grows.
Explanation: The best change is to implement the actual semantics of algorithmic efficiency. Growth in
required work can differ substantially among algorithms, affecting whether large inputs can be processed in
reasonable time. The distractors would produce misunderstandings or unnecessary restrictions. Correct use
depends on the construct's defined behavior, not on arbitrary rules.
Question 8. Which practice best demonstrates abstraction during development in the
development of a computing artifact?
A. Use well-defined procedures or data abstractions to manage complexity and hide unnecessary
implementation details.
B. Expose every low-level implementation detail to all parts of the program regardless of need.
C. Duplicate the same complex code in every place it is needed so each copy can evolve independently.
D. Avoid procedures and lists because abstractions always make programs harder to change.
Correct Answer: A. Use well-defined procedures or data abstractions to manage complexity
and hide unnecessary implementation details.
Explanation: The best answer describes abstraction during development as a deliberate development
practice. Abstraction reduces cognitive load and can improve reuse, organization, and maintainability. The
distractors either delay useful feedback, remove coordination, or substitute a weak proxy for the actual
practice. APCSP questions about development generally reward choices that use evidence, manage
complexity, and support reliable revision.
Question 9. A student is explaining procedures to a classmate. Which statement should
the student include?
A. Calling a procedure automatically repeats it forever. Therefore, it guarantees that a program has no
errors.
B. A procedure can be executed only once in a program. Therefore, the construct should be avoided.
C. A procedure groups instructions under a name so the program can invoke that behavior when needed.
This is useful because procedures support organization and reuse by encapsulating a defined
computation.
D. Every procedure must contain exactly the same statements as the main program. Therefore, it has no
effect on program design.
Correct Answer: C. A procedure groups instructions under a name so the program can invoke
that behavior when needed. This is useful because procedures support organization and reuse
by encapsulating a defined computation.
Explanation: The correct explanation accurately describes procedures and connects it to a valid benefit or
behavior. Procedures support organization and reuse by encapsulating a defined computation. Each distractor
begins from an incorrect claim and reaches an unsupported conclusion. A strong APCSP explanation states
both what a construct does and why that behavior matters.
Page 3
, Question 10. In AP pseudocode, list positions begin at 1. What value is displayed?
values ← [11, 22, 30, 41, 52]
index ← 4
result ← values[index]
DISPLAY(result)
A. 41
B. 52
C. 4
D. 5
Correct Answer: A. 41
Explanation: The variable index is assigned 4. Because AP pseudocode uses 1-based list indexing, values[4] is
41. The program therefore displays 41. Confusing 1-based indexing with 0-based indexing is a common
tracing error.
Question 11. A student is explaining correlation and causation. Which statement in the
explanation is a misconception?
A. Correlation can be computed only when one variable is Boolean.
B. The usefulness of a data technique depends on the question and the characteristics of the data.
C. A correlation between two variables does not by itself prove that changing one variable causes a
change in the other.
D. A careful analyst should consider how correlation and causation affects the meaning of a result.
Correct Answer: A. Correlation can be computed only when one variable is Boolean.
Explanation: The misconception is the claim that correlation can be computed only when one variable is
Boolean. Confounding variables, reverse causation, or coincidence can create associations without a direct
causal relationship. The remaining statements appropriately connect the concept to context and
interpretation. APCSP frequently tests whether students can reject overly broad claims about data.
Question 12. A city deploys an app that uses location data to suggest transit routes.
Which statement about open-source and content licenses is a misconception?
A. A license can grant permission to reuse or modify a work while imposing conditions such as
attribution, notice, or sharing requirements.
B. Different stakeholders may experience different consequences related to open-source and content
licenses.
C. Design and policy choices can influence how strongly open-source and content licenses affects users.
D. Every open license allows any use without attribution or other obligations.
Correct Answer: D. Every open license allows any use without attribution or other obligations.
Explanation: The misconception is the statement that every open license allows any use without attribution or
other obligations. Open licensing expands permitted reuse, but users still need to follow the specific terms
attached to the work. The remaining statements recognize that impacts vary across people and can be
influenced by design decisions. Negative-stem questions require identifying the one claim that contradicts
responsible computing principles.
Page 4
Practice Questions With Answers and Explanations
Question 1. Which statement about citizen science is most accurate?
A. Volunteer data is always unbiased because contributors are not paid.
B. Computing can let volunteers contribute observations or processing effort to scientific projects at
large scale.
C. Only professional scientists are allowed to contribute data to any scientific computing project.
D. Citizen science eliminates the need to validate measurements or methods.
Correct Answer: B. Computing can let volunteers contribute observations or processing effort
to scientific projects at large scale.
Explanation: The correct statement accurately describes citizen science. Distributed participation can expand
data collection and analysis while still requiring protocols, validation, and awareness of sampling limitations.
The distractors rely on absolute claims that ignore stakeholders, context, or known security and privacy
limitations. APCSP impact questions reward careful evaluation rather than assuming that computing is
automatically beneficial, neutral, or perfectly secure.
Question 2. Which statement best describes Internet Protocol and routing?
A. Routing requires the sender to know the exact sequence of every router before transmission begins.
B. An IP address guarantees that every packet follows a single permanent route.
C. Routers use destination addressing information to forward packets toward their destinations across
interconnected networks.
D. Routers inspect the meaning of every application message and rewrite it before forwarding.
Correct Answer: C. Routers use destination addressing information to forward packets toward
their destinations across interconnected networks.
Explanation: The correct choice gives the standard networking or computing meaning of Internet Protocol and
routing. Internet routing forwards packets hop by hop using addressing and routing information rather than a
preselected permanent path. The distractors confuse the concept with a different network property or make
an absolute guarantee that protocols cannot provide. APCSP systems questions emphasize how layered,
interoperable systems behave rather than assuming perfect networks.
Question 3. A developer argues that malware does not need to be considered because
the program works as specified. Which response is best?
A. The issue matters only if the program produces a syntax error.
B. The developer is correct because working code cannot create social, ethical, privacy, or security
concerns.
C. Technical correctness is not enough; malicious software is defined by harmful or unauthorized
behavior, not by device type or how the file first reached the system.
D. The developer is correct as long as the program has more than one user.
Correct Answer: C. Technical correctness is not enough; malicious software is defined by
harmful or unauthorized behavior, not by device type or how the file first reached the system.
Explanation: The best response explains that malicious software is defined by harmful or unauthorized
behavior, not by device type or how the file first reached the system. A program can execute exactly as
designed and still create harmful, unfair, insecure, or privacy-sensitive outcomes. The distractors confuse
technical correctness with responsible impact assessment. APCSP explicitly treats the effects of computing as
broader than whether code compiles and runs.
Page 1
,Question 4. A group is developing a tool that summarizes survey responses. The team
is reviewing its workflow. Which practice should be changed first because it conflicts
with collaboration?
A. Use clear task ownership, shared conventions, and regular communication when multiple people
develop a program.
B. Have every team member independently rewrite the entire program and combine the files at the end.
C. Avoid documenting interfaces because collaborators should infer how every component works.
D. Allow each collaborator to change shared code without communicating what was changed.
Correct Answer: D. Allow each collaborator to change shared code without communicating
what was changed.
Explanation: The practice that conflicts most directly with collaboration is the one that says to allow each
collaborator to change shared code without communicating what was changed. Collaboration is more effective
when contributors coordinate responsibilities, interfaces, version changes, and design decisions. The correct
workflow should make progress easier to evaluate and should reduce avoidable uncertainty. Identifying the
conflicting practice requires comparing each choice with the core purpose of the development principle.
Question 5. Consider the following code segment. What value is displayed when the
segment finishes?
x ← 5
y ← 6
x ← x + y
y ← x - 4
z ← 2 * y - x
DISPLAY(z)
A. 7
B. 3
C. 11
D. 2
Correct Answer: B. 3
Explanation: The code first changes x from 5 to 11. It then sets y to 7 because the updated value of x is used
in the assignment. Therefore z becomes 2 × 7 − 11 = 3. The key is to use each variable's most recently
assigned value when tracing later statements.
Question 6. A developer claims that debugging is unnecessary when a program is small.
Which response is most accurate?
A. The practice should be postponed until the program has been used for at least one year.
B. The practice matters only when the program will be sold commercially.
C. Even a small program can benefit because systematic debugging isolates causes and verifies
corrections rather than relying on random changes.
D. Small programs cannot contain logic errors, so the practice is useful only for large systems.
Correct Answer: C. Even a small program can benefit because systematic debugging isolates
causes and verifies corrections rather than relying on random changes.
Explanation: The claim is incorrect because systematic debugging isolates causes and verifies corrections
rather than relying on random changes. Program size can affect how much process is needed, but it does not
eliminate the underlying value of the practice. The distractors make unsupported absolute claims about size,
commercial use, or timing. APCSP emphasizes general development principles that apply at different scales.
Page 2
,Question 7. Which change would most directly help a programmer use algorithmic
efficiency correctly?
A. Adopt this rule instead: Algorithms that produce the same output always require the same number of
steps.
B. Adopt this rule instead: Efficiency matters only when a program contains no procedures.
C. Choose the implementation that reflects this principle: Two algorithms that solve the same problem
can require very different amounts of time as input size grows.
D. Adopt this rule instead: An algorithm that is fastest for one small input is guaranteed to scale best for
all larger inputs.
Correct Answer: C. Choose the implementation that reflects this principle: Two algorithms that
solve the same problem can require very different amounts of time as input size grows.
Explanation: The best change is to implement the actual semantics of algorithmic efficiency. Growth in
required work can differ substantially among algorithms, affecting whether large inputs can be processed in
reasonable time. The distractors would produce misunderstandings or unnecessary restrictions. Correct use
depends on the construct's defined behavior, not on arbitrary rules.
Question 8. Which practice best demonstrates abstraction during development in the
development of a computing artifact?
A. Use well-defined procedures or data abstractions to manage complexity and hide unnecessary
implementation details.
B. Expose every low-level implementation detail to all parts of the program regardless of need.
C. Duplicate the same complex code in every place it is needed so each copy can evolve independently.
D. Avoid procedures and lists because abstractions always make programs harder to change.
Correct Answer: A. Use well-defined procedures or data abstractions to manage complexity
and hide unnecessary implementation details.
Explanation: The best answer describes abstraction during development as a deliberate development
practice. Abstraction reduces cognitive load and can improve reuse, organization, and maintainability. The
distractors either delay useful feedback, remove coordination, or substitute a weak proxy for the actual
practice. APCSP questions about development generally reward choices that use evidence, manage
complexity, and support reliable revision.
Question 9. A student is explaining procedures to a classmate. Which statement should
the student include?
A. Calling a procedure automatically repeats it forever. Therefore, it guarantees that a program has no
errors.
B. A procedure can be executed only once in a program. Therefore, the construct should be avoided.
C. A procedure groups instructions under a name so the program can invoke that behavior when needed.
This is useful because procedures support organization and reuse by encapsulating a defined
computation.
D. Every procedure must contain exactly the same statements as the main program. Therefore, it has no
effect on program design.
Correct Answer: C. A procedure groups instructions under a name so the program can invoke
that behavior when needed. This is useful because procedures support organization and reuse
by encapsulating a defined computation.
Explanation: The correct explanation accurately describes procedures and connects it to a valid benefit or
behavior. Procedures support organization and reuse by encapsulating a defined computation. Each distractor
begins from an incorrect claim and reaches an unsupported conclusion. A strong APCSP explanation states
both what a construct does and why that behavior matters.
Page 3
, Question 10. In AP pseudocode, list positions begin at 1. What value is displayed?
values ← [11, 22, 30, 41, 52]
index ← 4
result ← values[index]
DISPLAY(result)
A. 41
B. 52
C. 4
D. 5
Correct Answer: A. 41
Explanation: The variable index is assigned 4. Because AP pseudocode uses 1-based list indexing, values[4] is
41. The program therefore displays 41. Confusing 1-based indexing with 0-based indexing is a common
tracing error.
Question 11. A student is explaining correlation and causation. Which statement in the
explanation is a misconception?
A. Correlation can be computed only when one variable is Boolean.
B. The usefulness of a data technique depends on the question and the characteristics of the data.
C. A correlation between two variables does not by itself prove that changing one variable causes a
change in the other.
D. A careful analyst should consider how correlation and causation affects the meaning of a result.
Correct Answer: A. Correlation can be computed only when one variable is Boolean.
Explanation: The misconception is the claim that correlation can be computed only when one variable is
Boolean. Confounding variables, reverse causation, or coincidence can create associations without a direct
causal relationship. The remaining statements appropriately connect the concept to context and
interpretation. APCSP frequently tests whether students can reject overly broad claims about data.
Question 12. A city deploys an app that uses location data to suggest transit routes.
Which statement about open-source and content licenses is a misconception?
A. A license can grant permission to reuse or modify a work while imposing conditions such as
attribution, notice, or sharing requirements.
B. Different stakeholders may experience different consequences related to open-source and content
licenses.
C. Design and policy choices can influence how strongly open-source and content licenses affects users.
D. Every open license allows any use without attribution or other obligations.
Correct Answer: D. Every open license allows any use without attribution or other obligations.
Explanation: The misconception is the statement that every open license allows any use without attribution or
other obligations. Open licensing expands permitted reuse, but users still need to follow the specific terms
attached to the work. The remaining statements recognize that impacts vary across people and can be
influenced by design decisions. Negative-stem questions require identifying the one claim that contradicts
responsible computing principles.
Page 4
