Just to make sure that I understand you correctly, these "student" RPis won't run Moodle servers, they are meant to be the students' client devices, to run the web browser and other desktop applications, right?
Then, by attaching monitors, keyboards and mice to the RPi, its main advantage, the portability, is lost. But if your aim ist just that, to permanently mount the RPis against theft, then it may be. The only observation I have is, if RPi for desktops, for that there is the Pi 400. I estimate both solutions to be substantially more expensive than cheap mobile devices.