AP Computer Science
Advanced Placement Computer Science (also called AP Comp Sci, APCS or AP Java) is the name of two distinct Advanced Placement courses and examinations offered by the College Board to high school students as an opportunity to earn college credit for a college-level computer science course. AP Computer Science A is meant to be the equivalent of a first-semester course in computer science, while AP Computer Science AB equated to a full year. The AP exam currently tests students on their knowledge of Java. AP Computer Science AB was discontinued following the May 2009 exam administration. The current Chief Reader for AP Computer Science is Liz Johnson, associate professor of computer science at Xavier University.
- 1 AP Computer Science A
- 2 AP Computer Science AB (discontinued)
- 3 Topic outline
- 4 AP Computer Science exam
- 5 Case Studies
- 6 Grade distributions for AP Computer Science A
- 7 Grade distributions for AP Computer Science AB
- 8 AP Computer Science: Principles
- 9 References
- 10 External links
AP Computer Science A
Advanced Placement Computer Science A emphasizes object-oriented programming methodology with an emphasis on problem solving and algorithm development. It also includes the study of data structures and abstraction, but these topics were not covered to the extent that they were covered in AP Computer Science AB.
AP Computer Science AB (discontinued)
Advanced Placement Computer Science AB included all the topics of AP Computer Science A, as well as a more formal and a more in-depth study of algorithms, data structures, and data abstraction. For example, binary trees were studied in AP Computer Science AB but not in AP Computer Science A. The use of recursive data structures and dynamically allocated structures were fundamental to AP Computer Science AB. Due to low numbers of students taking AP Computer Science AB, it was discontinued after the 2008-2009 year.
- Object-Oriented Program Design
- Program Design
- Read and understand a problem's description, purpose, and goals.
- Specify the purpose and goals for a problem. (AB only)
- Apply data abstraction and encapsulation.
- Read and understand class specifications and relationships among the classes ("is-a", "has-a" relationships).
- Decompose a problem into classes, define relationships and responsibilities of those classes. (AB only)
- Understand and implement a given class hierarchy.
- Identify reusable components from existing code using classes and class libraries.
- Class Design
- Design and implement a class.
- Design and implement a set of interacting classes. (AB only)
- Design an interface.
- Choose appropriate data representation and algorithms.
- Choose appropriate advanced data structures and algorithms. (AB only)
- Apply functional decomposition.
- Extend a given class using inheritance.
- Program Design
- Program Implementation
- Implementation techniques
- Programming constructs
- Java library classes (included in the A or AB-level AP Java Subset)
- Program Analysis
- Test classes and libraries in isolation
- Identify boundary cases and generate appropriate test data
- Perform integration testing
- Understand and modify existing code
- Extend existing code using inheritance
- Understand error handling
- Understand runtime exceptions
- Throw runtime exceptions (AB only)
- Reason about programs
- Analysis of algorithms
- Numerical representations and limits
- Standard Data Structures
- Standard Algorithms
- Computing in Context
- Major hardware components
- System software
- Types of systems
- Single-user systems
- Responsible use of computer systems
AP Computer Science exam
The AP exam currently tests students on their knowledge of computer science through Java. Before 1999, the AP exam tested students on their knowledge of Pascal. From 1999 to 2003, the exam tested students on their knowledge of C++ instead. The AP exam in Computer Science was first offered in 1984.
The exam is composed of two sections:
- Section I: Multiple Choice [1 hour and 15 minutes for 40 multiple-choice questions]
- Section II: Free-Response [1 hour and 45 minutes for 4 problems involving extended reasoning]
The AP exam has used several programs in its free-response section to test student's knowledge of object-oriented programs without requiring them to develop an entire environment. Currently, the test uses the GridWorld case study.
GridWorld Case Study
The GridWorld Case Study is intended to be a substitute for writing a single large program as a culminating project. Due to obvious time restraints during the exam, the GridWorld Case Study is provided by the College Board  to students prior to the exam. They are expected to be familiar with the classes and interfaces (and how they interact) before taking the exam. The case study is divided into five sections, the last of which was only tested on the AB exam.
Roughly five multiple-choice questions in Section I are devoted to the GridWorld Case Study, and it is the topic of one free response question in Section II.
The GridWorld Case Study replaced the Marine Biology Case Study for the 2007-2008 school year, and has been continued as the case study up till now. It has been slated for removal; the 2014 exam may be the last one in which it appears. Three new labs will replace it for use in AP courses, though the new labs will not actually be tested. 
Marine Biology Case Study
The Marine Biology Simulation Case Study (MBCS) was a program written in C++ until 2003, then in Java, for use with the A and AB examinations. It served as an example of object-oriented programming (OOP) embedded in a more complicated design project than most students had worked with before. It replaced the Big Integer case study that was in use prior to 2000.
The case study was designed to allow the College Board to quickly test a student's knowledge of object oriented programming ideas such as inheritance and encapsulation while requiring students to understand how objects such as "the environment", "the fish", and the simulation's control module interact with each other without having to develop the entire environment independently, which would be quite time consuming. The case study also gives all students taking the AP Computer Science exams with a common experience from which to draw additional test questions.
On each of the exams, at least one free-response question was derived from the case study. There were also five multiple-choice questions that are derived from the case study.
This case study was discontinued from 2007, and was replaced by GridWorld.
Grade distributions for AP Computer Science A
In the 2012 administration, 26,103 students took the exam. The mean score was a 3.06 with a standard deviation of 1.55. The grade distribution since 2003 was:
Grade distributions for AP Computer Science AB
2013 score distribution may shift slightly as late exams are scored.
In the 2008 administration, 4,995 students took the exam. The mean score was a 3.52. The grade distribution for 2008 was:
AP Computer Science: Principles
A new exam, titled Advanced Placement Computer Science: Principles is currently under development. It is designed not to be a replacement for AP Computer Science A, but rather as a parallel option that will focus on computational thinking and fluency. The project is being led by Prof. Owen Astrachan, Professor of the Practice of Computer Science at Duke University. Pilot materials are currently being created, with pilot studies planned to run from the end of 2010 through 2016.
- AP Computer Science A Home Page, The College Board
- AP Computer Science AB Home Page, The College Board
- AP Computer Science AB Home Page
- Johnson, Dr. Liz 
- Cech, Scott J., "College Board Intends to Drop AP Programs in Four Subjects", Education Week, 9 April 2008
- "Computer Science A Course Description" (PDF). College Board. Fall 2010. pp. 8–10. Retrieved 5 March 2012.
- "Computer Science A Computer Science AB Course Description" (PDF). College Board. May 2009. pp. 10–13. Retrieved 5 March 2012.
- Diaz, Lien. "AP Computer Science Program From Case Study to Labs". Retrieved 2013-06-28.
- "2011 Computer Science A Score Distribution". College Board. Retrieved 5 March 2012.
- "2008 Computer Science AB Grade Distribution". College Board. Archived from the original on 20 June 2009. Retrieved 5 March 2012.
- Astrachan, Owen (29 October 2010). "Owen Astrachan Statement of Support". Retrieved 5 March 2012.
- Home page for Owen Astrachan
- "Proposed New Course and Exam—AP® Computer Science: Principles". College Board. Retrieved 5 March 2012.
- "CS Principles, A New First Course in Computing". csprinciples.org. College Board. Retrieved 5 March 2012.