Effective Succinct Feedback for Intro CS Theory: A JFLAP Extension

ABSTRACTComputing theory is often perceived as challenging by students, and verifying the correctness of a student's automaton or grammar is time-consuming for instructors. Aiming to provide benefits to both students and instructors, we designed an automated feedback tool for assignments where students construct automata or grammars. Our tool, built as an extension to the widely popular JFLAP software, determines if a submission is correct, and for incorrect submissions it provides a "witness" string demonstrating the incorrectness. We studied the usage and benefits of our tool in two terms, Fall 2019 and Spring 2021. Each term, students in one section of the Introduction to Computer Science Theory course were required to use our tool for sample homework questions targeting DFAs, NFAs, RegExs, CFGs, and PDAs. In Fall 2019, this was a regular section of the course. We also collected comparison data from another section that did not use our tool but had the same instructor and homework assignments. In Spring 2021, a smaller honors section provided the perspective from this demographic. Overall, students who used the tool reported that it helped them to not only solve the homework questions (and they performed better than the comparison group) but also to better understand the underlying theory concept. They were engaged with the tool: almost all persisted with their attempts until their submission was correct despite not being able to random walk to a solution. This indicates that witness feedback, a succinct explanation of incorrectness, is effective. Additionally, it assisted instructors with assignment grading.