The Schola Progenium are schools for orphans run by the Ecclesiarchy in Warhammer 40,000. Its various students come from all walks of life (as long as their parents died in service of the Imperium), and regardless of what they were before entering, they come out as dangerous, Emperor-loving killing machines (or corpses). In the Schola Progenium, a child is trained daily in how to read Ecclesiarchial scripture, hold and shoot .75-caliber automatic rocket launchers, identify dangerous and heretical individuals, and how to sip tea.
Schola facilities are NOT like Hogwarts, they are grim and unwelcoming places (like Hogwarts in the last two movies), designed to keep students free from frivolous distraction and entirely focused on whatever it is they are learning. This, however, does not seem to be completely effective, given the case of Ciaphas Cain, for example, who did below-average in everything but his combat and sports subjects and has been hinted in his biography to have been a bit of a problem student, although he was never caught to be officially disciplined (probably because he didn't get caught).
They are also under constant surveillance, with recording servo-skulls patrolling constantly to report the whereabouts and behaviour of each student, and a number of hidden passageways for tutors to be able to keep students on their guard.
Scholae are built like fortresses, though with their battlements facing inwards, like prisons, to stop students from escaping.
"No no no! By the Throne, boy, how many times? Depress the loading catch before removing the drum feed, not while removing the drum feed! You'll jam the weapon! *smack* Oh stop bawling, child. You're ten years old, you should have learned basic autogun procedures by now. Fifty press ups and fifty Pax Imperiums. And certainly there will be no dinner."
- – Drill Abbott Kross Vorgt
While there are specialist teachers of particular subjects in the Schola Progenium, most of the instructors are Drill Abbots, who are ordained priests of the Ecclesiarchy, but they get excused from all the onerous jobs like taking Sunday mass, performing weddings, and baptising babies.
Instead, their job is to teach the Imperial Creed, physical education, weapons training, and also to enforce discipline.
Typical of the 41st millennium, there is no standard of basic human rights, so discipline at school can take a multitude of forms, from branding to sleep deprivation, even battering them on the head with a sledgehammer if they think the student needs a firm hand. Handing "live" weaponry to abuse victims is standard Imperial logic at its best.
Drill Abbots can also come from a variety of backgrounds, despite being priests. Many are transferred over from the Imperial Guard, where a number of desirable skills are transferable to the role, making many of them Drill Instructors as well as Abbots.
Not just any orphan is granted admission to the Schola Progenium, no sir. With the amount of war and death in the Imperium orphans are a dime a dozen, plus tuition fees are expensive, so the Imperium reserves the use of Schola facilities for only the "finest" prospective students.
To be admitted you have to be the offspring of someone notable; whether it is the child of an officer of the military or any other branch of the Adeptus Terra for that matter, or the scion of a noble house whose parents have fallen to ill-circumstance.
In fact, it has been rumored that such ill-circumstance has occasionally been via the Schola Progenium itself when they scout out a good prospective candidate and want to separate them from their parents.
That all having been said, few tithes take whole families as that tends to be a non-sustainable way of spending the Emperor's currency. Actual orphans tend to be more the result of mischance than malevolence or heavy-grinding campaigns.
Upon arrival, students receive chemical mind-wiping to strip away any connection with their former life, remove any trauma that might have occurred when making them orphans, and to provide a fresh canvas to mold the students into ideal AND LOYAL subjects of the Imperium. Though it seems this step isn't mandatory, as Ciaphas Cain still looks up to his scumbag parents and fondly remembers his home planet, wherever it actually is (Amberley doesn't even know, and if anyone could find out...), and that's assuming he's not just confabulating wildly inconsistent stories about a largely imagined childhood.
They also receive new names, though siblings from the same family get assigned the same surnames since the Schola has found sibling rivalry to be an excellent tool for motivation.
This is actually quite a difficult period for any prospective mature student; despite the fact that he may be much older and experienced than his high-school aged classmates, the Schola itself makes no special distinction between them.
Due to his varied background, his range of education may be vastly inferior to that of the other progenia, particularly if he originally came from a feral world or underhive. As such, he will probably be far behind his classmates, and end up pissing off his instructors to no end, who can't deal with a war veteran exposed to daemonic infohazards and aliens who is likely suffering from PTSD and can probably tear them limb from limb out of experience.
- It's quite ironic, since according to the RPG rules, Storm Troopers are ascension (lv9+) characters whilst Drill Abbots are lv5+ guardsmen so it is quite possible for a Guardsman character to become a Drill Abbot FIRST and THEN a Storm Trooper.
Those who can, do; those who can't, teach.
Despite the harsh regime under which progenia have to live, the level of physical and mental training afforded to them makes them some of the most highly educated and fit people in the Imperium.
Each progenium, regardless of their final career path will have a functioning knowledge of the Administratum, the Ecclesiarchy and the Imperial Creed, Imperial History and Philosophy, as well as fluency in High Gothic.
They will also have rudimentary training in close quarters combat and basic ranged weaponry, so even your schola-trained Administratum drone can be a reasonably even match-up with a normal Guardsman past his basic training.
Later in their schooling, the progenia will be bundled into groups matching their aptitudes; for example those with a talent for investigation are steered towards Arbites training. Eventually culminating in the final Test of Compliance to prove their suitability:
- Tempestus candidates are made to undergo a live fire exercise without any prior notice, to prove that they can respond quickly enough to survive as well as work efficiently as a team. These exercises are often performed in a Hallucinarium which is a labyrinth that exposes the cadets to strange visions and orders. The point of this is to make sure that the cadets will follow orders even when confused or receiving contradictory inputs.
- Future Commissars are handed a pistol and told to execute one of their poorly performing classmates in order to make certain that the student will act without hesitation and is loyal to the cause. The schola tries to make it one of their close friends if they can, so that it is not too easy for the cadet if they just didn't like the target- and more importantly, ensure that their loyalty to the Imperium and willingness to follow orders comes before any kind of personal relationship. If they refuse or take too long, they'll probably end up getting shot by another student on his own way to becoming a commissar instead.
- Despite the common belief that female graduates "usually" get shuffled off to the various institutions of the Adepta Sororitas, the fact is that the Sisterhood only wants young women of particularly strong faith and are very picky over who joins their convents, so female progenia can end up in other organisations just as frequently as the males. That being said; in the 41st Millennium, fanatical faith is never in short supply so the Sororitas can draw the majority of their recruits from the Schola.
- Candidates for the Officio Assassinorum just vanish when it gets close to Selection Day. Despite all of the testing and prep work they've already done in the Schola, the true training only starts on the ship back to the Terra, with conditions so extreme that attrition rates of 90%+ are common. THEN they need to spend a further ten years as an apprentice before they even get considered for their first assignment.
- The Inquisition gets free run of Scholas to pick and choose whichever candidates they like. Though when they come to visit, often the best candidates will be inexplicably absent on field trips or recovering from injury in the infirmary. The Inquisition also takes a deep interest in truants, since it takes a lot of motivation and resourcefulness to escape from the facilities.
Note: The codexes and RPG rulebooks are contradicted by the 40K novel series' entries, which make no mention of Drill Abbots or graduate Commissars executing anybody. The sixth Cain book takes place in a Schola, and none of this shit happens at all, though his books are framed as a first person autobiography, so he can include or neglect whatever he likes (and any Schola run by him probably wouldn't have that anyway, as his distaste for the "standard" Commissariat conduct is well documented, and every graduate that doesn't get shot by one of his classmates is one more for Cain to hide behind). Also, there are hundreds, if not thousands, of different scholas across the galaxy and each works according to its own idiom. (That, and the tests of compliance were added in a codex written after that particular book.)
Progenia of each Schola are ideal members of just about every branch of the Imperium. They make good clerks (need to be able to hold a bolter when some punk comes in with a knife), adepts of the Administratum (only a man who loves the Emperor dearly can bear with writing for a 20-hour workday), and especially good Arbitrators, for obvious reasons. They are also prime candidates for joining the Inquisition. They often become Commissars or Storm Troopers in the Imperial Guard, and only promising and fanatically zealous female graduates may join the Adepta Sororitas... usually.
Basically if you are anyone important while remaining mortal, you are either a Schola graduate or survived several decades of war, which isn't easy.