An improper shutdown procedure can easily lead to the SD getting corrupted. In other words, if a student yanks the power cable suddenly from the Pi, the filesystem on the SD will probably be corrupted and will need repair at reboot. Rarely the FS is so badly damaged that automatic repair at boot time is not possible. Rarely as well, the SD can die altogether and need replacing.
With a read-only filesystem, corruption cannot happen as the system is immutable and the SD is only read from, never written. There might remain a small window where the FS needs to be set read/write and destroying the SD is possible, e.g. during boot or while upgrading the system.
Which OS are you running?
Raspbian/Debian is by and large not able to run off a read-only filesystem. You can change that (mostly) but it is a bit of work and might cause issues if you upgrade.
Something like piCore is designed to run off an RO filesystem. Very different from Debian/Raspbian. Excellent hardware support.
But in your case, perhaps piNet
would be the best solution? Network booting, no SD at all (or a minuscule one that can really be read-only, just for holding the firmware files). Wired network required, though.