Insights from Student Solutions to MongoDB Homework Problems

Reviewed by Donny Winston / 2021-10-10
Keywords: Computing Education, Databases, Novices

Alkhabaz2021 tries to determine what concepts are difficult for students when learning MongoDB, and what common errors students make when first learning to query a MongoDB database. I came away not quite understanding the authors' conclusions, but I did encounter two observations that surprised me:

  • 3.5% of student submissions "were omitted from this study, because they had a common error where students copied JavaScript code from online sources, causing the interpreter to fail due to an unexpected unicode character." That seems like a lot to me, and highlights the prevalence of "copy-and-paste" programming even in early computing education.
  • 47% of all submissions resulted in "incorrect result set" (versus "mongodb error", "javascript error", or "correct"), that is a "silent" error. In retrospect, this should not have surprised me as much as it did. Others such as Rich Hickey ([talk](, [transcript](, [slides]( have insisted that most of problems in the practice of programming are above the "language model complexity" level, such as dealing with misconceptions.

Alkhabaz2021 Ridha Alkhabaz, Seth Poulsen, Mei Chen, and Abdussalam Alawini: "Insights from Student Solutions to MongoDB Homework Problems". Proc. Conference on Innovation and Technology in Computer Science Education (ITiCSE), 2021, 10.1145/3430665.3456308.

We analyze submissions for homework assignments of 527 students in an upper-level database course offered at the University of Illinois at Urbana-Champaign. The ability to query databases is becoming a crucial skill for technology professionals and academics. Although we observe a large demand for teaching database skills, there is little research on database education. Also, despite the industry's continued demand for NoSQL databases, we have virtually no research on the matter of how students learn NoSQL databases, such as MongoDB. In this paper, we offer an in-depth analysis of errors committed by students working on MongoDB homework assignments over the course of two semesters. We show that as students use more advanced MongoDB operators, they make more Reference errors. Additionally, when students face a new functionality of MongoDB operators, such as \texttt{\$group} operator, they usually take time to understand it but do not make the same errors again in later problems. Finally, our analysis suggests that students struggle with advanced concepts for a comparable amount of time. Our results suggest that instructors should allocate more time and effort for the discussed topics in our paper.