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 is only tested on the AB exam.
Roughly five multiple-choice questions in Sections 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.
Marine Biology Case Study
The Marine Biology Simulation Case Study (MBCS) was a program written 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.