Helping tools for the regular expression author for test questions in LMS Moodle

Abstract

Composing regular expressions for test questions is often a difficult thing for the teachers; so many teachers avoid using regular expression questions. Similar problems hinder students learning regular expressions as a part of computer science. There are many programs developed to help composing and learning of the regular expressions, but they are using different forms of regular expression visualization. The goal of this research was to compare efficiency of different forms of regular expression representation for their learning and composing, methods for linking them together and with regular expression text. A set of helping tools for regular expressions authors (as a plugin for Moodle CMS) was developed, using three form of regular expression representation: syntax tree (visualizes expression structure), explanation graph (visualizes paths of expression execution) and text description – and testing tool, showing regular expression match with test strings. Developed instruments was used by students learning regular expressions, the students fill a survey after that. Students were divided into four groups by their year of study and country. Survey shows that different group of students prefer different instruments. Most generally popular ones were explanation graph and regular testing, but even text description – a general outsider – was leading in the group of students from Africa learning in English language. The survey also shows that ability to select part of regular expression representation and see that part selected in other representations and regular expression text was very useful in linking representations together and understanding complex expressions. About a quarter of students used other regular expression construction tools before taking part in this experiment, most of them said that developed tools were better than those they used before. Several teachers, which had used regular expressions in their questions, have written reviews stating that developed instruments make learning regular expressions easier and help debug regular expressions in their questions. So, the survey of students and teachers reviews shows that system of several regular expression representations linked together by subexpression selection is more effective that any particular representation in itself; different classes of users prefer different forms of representation. Including helping tools for regular expression authors in the quiz creation software allows increasing the use of regular expressions for quiz questions and helps test and debug them.