From what I have read, on the outside they are focused on art studies. But if we look at the harsh training before their debuts, I think that school teachers have no time to provide a proper education on a variety of subjects. Do they have normal school events or days off? I highly doubt it.
Mainly it's a restricted environment where the minors are taught very specific things for few hours so they have time to practice singing/dancing with the other trainees. I am sure other brain washing takes place as well. Social isolation, repetition, malnutrition and sleep deprivation are all prime abuse/brain washing tactics. And they are all happening routinely before the trainees debut.
Abuse is being brushed off as "wow this idol is so hard working, before their debut they only ate an apple every 2 days and practiced until they collapsed and slept no more than 3 hours per day". So destructive and irrational, UNLESS it's part of mind control and the creation of slaves.
And what happens to those who -for whatever reason- fail to debut?