Paper vs. Computer-based Exams: A Study of Errors in Recursive Binary Tree Algorithms

摘要

This paper reports on a study of goal-plans and errors produced by students who wrote recursive solutions for a binary tree operation. This work extends a previous study of difficulties CS2 students experienced while writing solutions on paper-based exams. In this study, participants solved the same recursive binary tree problem as part of a hands-on computer-based exam where students had access to an IDE and Java API documentation. Not surprisingly, students who took the computer-based exams were more successful than those who took the paper-based exams (58% vs. 17% correct solutions). However, even with the advantage of access to an IDE, documentation, and test cases, 42% of students taking the computer-based exam still made errors, indicating that students exhibit persistent errors even with support. The most common errors observed included incorrect calculations, missing method calls and missing and incorrect base cases.