Evaluating and improving the Usability of MIT App Inventor

Abstract

MIT App Inventor is a blocks-based programming language for Android apps designed to teach programming skills to middle school and high school students. We aim to make app development accessible for all. Anyone learning to program must learn computational thinking methods; App Inventor users must also learn how to use the service. Our target users, teenagers and people without programming experience, often conflate the two learning processes: they think App Inventor is hard because learning to program is hard. As such, App Inventor needs a user interface that matches the conventions of commercially-available software our users already know how to use. Such an interface will allow them to focus on learning how to program and to transfer their knowledge and skills to other programming languages and environments. I designed several tasks and conducted a usability study on the existing, publicly-available App Inventor service. Users encountered 75 unique issues and a total of 157 issues. This is an average of 5 unique issues and 10.5 total issues per user. I made changes to the App Inventor source code that addressed 34 of the most common issues encountered. My intent was to make App Inventor both more usable to novice programmers and more similar to the programming environments that experienced programmers use. Finally, I conducted a usability study with the same tasks on the modified version of App Inventor. Users encountered 65 unique issues, including 19 issues encountered in the first study, and 107 total issues. Based on user comments and behavior, I conclude that my solutions resolved 21 of the original issues, partially mitigated 9 issues, and did not improved the usability of 4 issues..