AP Computer Science Principles

What the course covers

5 units, with exam weights

1. Unit 1

   Creative Development

   10-13% of examFree
   How programs actually get made: collaboration, describing what a program does and for whom, iterative and incremental development, documentation and credit, and finding and fixing errors through testing. This unit is also the backbone of the Create performance task.
   4 topics

   1. 1.1Collaboration
   2. 1.2Program Function and Purpose
   3. 1.3Program Design and Development
   4. 1.4Identifying and Correcting Errors

2. Unit 2

   Data

   17-22% of exam
   Bits as the universal representation: binary numbers, fixed bit widths and their limits (overflow, rounding), analog versus digital data, lossless versus lossy compression, and how data and metadata are cleaned, processed, and visualized to produce knowledge, along with the limits of that knowledge.
   4 topics

   1. 2.1Binary Numbers
   2. 2.2Data Compression
   3. 2.3Extracting Information from Data
   4. 2.4Using Programs with Data

3. Unit 3

   Algorithms and Programming

   30-35% of exam
   The heaviest unit. Variables, lists, strings, arithmetic and Boolean expressions, conditionals, loops, and procedures in the AP pseudocode; developing and comparing algorithms; list traversal and binary search; libraries, randomness, and simulation; efficiency and heuristics; and problems no algorithm can decide.
   18 topics

   1. 3.1Variables and Assignments
   2. 3.2Data Abstraction
   3. 3.3Mathematical Expressions
   4. 3.4Strings
   5. 3.5Boolean Expressions
   6. 3.6Conditionals
   7. 3.7Nested Conditionals
   8. 3.8Iteration
   9. 3.9Developing Algorithms
   10. 3.10Lists
   11. 3.11Binary Search
   12. 3.12Calling Procedures
   13. 3.13Developing Procedures
   14. 3.14Libraries
   15. 3.15Random Values
   16. 3.16Simulations
   17. 3.17Algorithmic Efficiency
   18. 3.18Undecidable Problems

4. Unit 4

   Computer Systems and Networks

   11-15% of exam
   How devices form networks and how the Internet works: packets, routing, bandwidth, open protocols (IP, TCP, UDP, HTTP), the Internet versus the Web, redundancy and fault tolerance, and the speedup limits and benefits of parallel and distributed computing.
   3 topics

   1. 4.1The Internet
   2. 4.2Fault Tolerance
   3. 4.3Parallel and Distributed Computing

5. Unit 5

   Impact of Computing

   21-26% of exam
   Computing in society: beneficial and harmful effects (often from the same innovation), the digital divide, bias embedded in data and algorithms, crowdsourcing and citizen science, intellectual property and licensing, and safe computing from personal data and privacy to encryption, authentication, malware, and phishing.
   6 topics

   1. 5.1Beneficial and Harmful Effects
   2. 5.2Digital Divide
   3. 5.3Computing Bias
   4. 5.4Crowdsourcing
   5. 5.5Legal and Ethical Concerns
   6. 5.6Safe Computing

The exam, part by part

2 parts, 3 h in all.

• Section I: Multiple Choice

  Questions

  70

  Time

  2 h

  Weight

  70%

  No calculator

  Format details

  Four answer choices (A to D) on every item. The questions appear in this order: 57 single-select items, then one set of 5 single-select items built on a reading passage about a computing innovation, then 8 multiple-select items where exactly two choices are correct. Code appears in the AP pseudocode from the Exam Reference Sheet, in text or block form, and some items use a robot on a grid. Every Big Idea is tested: Creative Development 10-13%, Data 17-22%, Algorithms and Programming 30-35%, Computer Systems and Networks 11-15%, Impact of Computing 21-26%.

• Section II: Create Performance Task Written Response

  Questions

  2

  Time

  1 h

  Weight

  30%

  No calculator

  Format details

  Task types: Written Response 1, Written Response 2

  Two questions with four prompts in total: Written Response 1, then Written Response 2 parts (a), (b), and (c). On the real exam every prompt is about the student's own program, answered with their printed Personalized Project Reference (PPR). In mock exams the PPR is a sample program provided with each question. The 30% weight covers the whole Create task: six 1-point rows, two scored from the submitted video and program code before exam day and four from these written responses.

Skills the exam scores

• 1.AInvestigate the situation, context, or task

  Work out what a problem actually asks and what constraints apply before choosing a computational approach. (Practice 1: Computational Solution Design)

• 1.BDesign an appropriate method or approach

  Plan a development process or approach that fits the purpose, such as iterative design, testing strategy, or user feedback. (Practice 1)

• 1.CExplain how collaboration affects a solution

  Explain how teams, diverse perspectives, and large-scale participation change what gets built and how well it works. (Practice 1)

• 1.DEvaluate solution options

  Compare alternatives such as compression schemes, algorithms, parallel versus sequential solutions, or fault-tolerant designs, and justify the better choice for a context. (Practice 1)

• 2.ARepresent algorithms without a programming language

  Express sequencing, selection, and iteration in plain language, flowcharts, or step lists. (Practice 2: Algorithms and Program Development)

• 2.BImplement and apply an algorithm

  Write or complete code that correctly carries out an algorithm, including filling in missing code. (Practice 2)

• 3.AGeneralize data sources through variables

  Represent values, lists, and strings with variables so a program works for many inputs. (Practice 3: Abstraction in Program Development)

• 3.BUse abstraction to manage complexity

  Use lists and procedures (with parameters) to organize a program so it is easier to write, read, and change. (Practice 3)

• 3.CExplain how abstraction manages complexity

  Explain what detail an abstraction hides, from bits representing data to procedures and lists in code. (Practice 3)

• 4.AExplain how code functions

  Describe what a program or code segment does and why, including its inputs, outputs, and purpose. (Practice 4: Code Analysis)

• 4.BDetermine the result of code segments

  Trace code precisely to find displayed output, final variable values, or side effects. (Practice 4)

• 4.CIdentify and correct errors

  Find logic, syntax, run-time, and overflow errors, including by choosing test inputs with known expected outputs, and fix them. (Practice 4)

• 5.AExplain how computing systems work

  Explain networks, the Internet, protocols, routing, fault tolerance, and parallel or distributed computing. (Practice 5: Computing Innovations)

• 5.BExplain how knowledge is generated from data

  Explain how data and metadata are processed to reveal trends, patterns, and insights, and what limits those conclusions. (Practice 5)

• 5.CDescribe the impact of a computing innovation

  Describe beneficial and harmful, intended and unintended effects, and who is affected, including the digital divide. (Practice 5)

• 5.DDescribe the impact of gathering data

  Describe privacy risks and consequences of collecting, storing, and combining personal data. (Practice 5)

• 5.EEvaluate computing on legal and ethical grounds

  Weigh bias, intellectual property, licensing, security, and misuse of computing resources. (Practice 5)

• 6.ACollaborate in developing solutions

  Work effectively in teams: communicate, give and use feedback, and resolve conflict. Not assessed on the exam. (Practice 6: Responsible Computing)

• 6.BUse safe and secure methods

  Protect devices, accounts, and personal information in everyday computing. Not assessed on the exam. (Practice 6)

• 6.CAcknowledge intellectual property

  Credit code, media, and ideas taken from others, including in the Create task. Not assessed on the exam. (Practice 6)