In Greek history, the term Krifó scholió (Greek "κρυφό σκολειό" or "κρυφό σχολείο", lit. "Secret school") refers to illegal underground schools for teaching the Greek language and Christian doctrines, provided by the Greek Orthodox Church under Ottoman rule in Greece between the 15th and 19th centuries. Against this view, many historians agree that there is no historical evidence that such schools ever existed. Others believe that secret schools did exist during periods of intense islamisation. Much schooling was probably done through small-scale, privately organized teaching in churches and monasteries. There are scarce written evidence that schooling was illegal or repressed under certain conditions not only for Greeks but also for Albanians. The narrative of "Kryfo Scholio" became the target of a political and ideological polemic in late 20th century and was omitted from the school textbooks in an attempt of reconstruction of the national identity.
There are evidences (mostly in greek language) that the Ottoman authorities prohibited education in the languages of non-Muslim subject peoples in certain periods and places, in the frame of the islamic law of sharia. Greeks were therefore forced to cater for their basic education needs through small, sometimes secretly organized underground schools, which were run in monasteries and churches under the pretext of religious education which was permitted. Sites of such secret schools are today shown in many places in Greece.[examples needed] These schools are often credited with having played a decisive role in keeping Greek language and literacy alive through the period of Turkish rule.
Τhe narrative of the secret schools became popular after Greece had begun its War of Independence in 1821. The first mention of such schools has been traced to 1825, in a work of the German scholar Carl Iken, quoting information given to him by a Greek scholar, Stephanos Kanellos. One of the few scholarly works that has seriously argued for the existence of such schools was written by G. Chassiotis in 1881; Gritsopoulos has also published works supporting their existence, though allowing for the continuation of Greek-language higher education in Constantinople in the early Ottoman empire.
The notion of the secret school became more popular and more entrenched in the collective memory of Greeks through a painting of that name by Nikolaos Gyzis, of 1885-86 (today in the Emphietzoglou Collection, Athens). It depicts a romanticized scene of such a school, with the venerable figure of an old orthodox priest reading by candlelight to a group of boys and young men in the traditional attire of Greek klephts.
Απ' έξω μαυροφόρ' απελπισιά,
πικρής σκλαβιάς χειροπιαστό σκοτάδι,
και μέσα στη θολόκτιστη εκκλησιά,
στην εκκλησιά, που παίρνει κάθε βράδυ
την όψη του σχολειού,
το φοβισμένο φως του καντηλιού
τρεμάμενο τα ονείρατα αναδεύει,
και γύρω τα σκλαβόπουλα μαζεύει.
Outside, black desperation,
tangible shadow of bitter slavery,
but inside in the vaulted church,
the church which assumes every night
the shape of a school,
there is the shivering light of the candle
lighting up the dreams
and collecting the children of the slaves from all around.
Krifo scholio as a myth
Among scholars who argued against the existence of the "secret schools" as early as the first half of the 20th century, were the historians Dimitrios Kambouroglou, Manuel Gedeon, and Yannis Vlachoyannis.
Within the Ottoman millet system, the Ecumenical Patriarchate of Constantinople was responsible for most aspects of civil administration for the Christian population, and it had a high degree of autonomy in running its own affairs. Hence the church was free to run schools wherever it desired. However, the permition to operate schools (as well as to repair churches etc) was often obtained through heavy brivery to Ottoman authorities. The existence of many public, legally operated Greek schools is in fact well attested, especially in the larger towns after the 17th century, although the church never went so far as to organize a full-scale school programme for the whole of the population.
Another approach accepts that Ottoman administration did not try to forbid Greek or Christian schools, but argues that patriotic ideas, national consciousness and modern Greek history were spread through secret lessons given in secret places, by teachers propagating the idea of national liberation.
- Hedge school, in Irish history
- Alkis Angelou, Κρυφό Σχολείο: το χρονικό ενός μύθου (Secret school: the chronicle of a myth), Athens: Estia, 1997.
- Christos G. Patrinelis: "Η διδασκαλία της γλώσσας στα σχολεία της Τουρκοκρατίας" ("Language [i.e. Greek] teaching in schools of the Turkish period"). In: M. Z. Kopidakis (ed.), Ιστορία της Ελληνικης Γλώσσας (History of the Greek Language) Athens: Elliniko Logotechniko kai Istoriko Archeio. 216-217.
- Veremis Thanos, interview, "Sky" TV Channel, Greece, Feb. 28, 2011, in greek language.
Thanos Veremis is Professor of Political History at the University of Athens 
- Kostovicova Denisa, "Shkolla Shqipe" and Nationhood, in Stephanie Schwandner-Sievers & Bernd Jürgen Fischer, "Albanian Identities", Indiana University Press, 2002 p. 162.
- ">Meselidis Stylianos, Teachers, History Wars and Teaching History Grade 6 in Greece, in Joseph Zajda, Globalisation, Ideology and Education Policy Reforms, Springer, 2010, pp. 39-48
- Noehden (G. H.), "On the Instruction and Civilisation of Modern Greece», The Classical Journal 21 (1820), p. 192.
- René Puaux, The sorrows of Epirus, Hurst & Blackett, London, 1918, p. 103: (referring to Greeks in Epirus under Ottoman rule, 1913) "No Greek book printed at Athens was allowed into schools. Everything had to come from Constantinople. Greek history was forbidden. Accordingly, they gave extra lessons in secret, and at these, without book or paper, the little Epirote learnt to know his motherland, its national hymn, ..."
- George Chassiotis: L'instruction publique chez les Grecs: depuis la prise de Constantinople par les Turcs jusqu' à nos jours. Paris, 1881.
- Antonis Danos "Nikolaos Gyzis's The Secret School and an ongoing national discourse". Nineteenth-Century Art Worldwide 1 (2002).
- Ioannis Polemis: "Το κρυφό σχολειό" Online text of the poem (in Greek)[not in citation given].
- Hellinomnimon Project: "Greek Higher Schools (1620-1821)". University of Athens.  Archived January 5, 2006 at the Wayback Machine
- Apostoliki Diakonia of the Church of Greece, Το Κρυφό Σχολειό: Μύθος ή Πραγματικότητα;, 2007
- Giorgos Kekavmenos, Το Κρυφό Σχολειό κι η Ιστορία: Οι πηγές, οι μαρτυρίες, η αλήθεια, 2008. ("The Secret School and the History: The sources, the testimonies, the truth")
- Kyriakos I. Finas, Το Κρυφό Σχολειό: Μύθος ή Πραγματικότητα; (The Secret School: Myth or Reality?), 2007 Archived January 18, 2008 at the Wayback Machine
- Fanis Kakridis, Άσκηση από-απομυθοποίησης: Το Κρυφό Σχολειό, Δωδώνη: Φιλολογία (University of Ioannina) 308-309:279-295 full text
- Alkis Angelou, Κρυφό Σχολείο: το χρονικό ενός μύθου (Secret school: the chronicle of a myth') (Athens: Estia, 1997) ISBN 960-05-0770-8.
- George Chassiotis, L'instruction publique chez les Grecs: depuis la prise de Constantinople par les Turcs jusqu' à nos jours. Paris, 1881.
- Antonis Danos, "Nikolaos Gyzis's The Secret School and an ongoing national discourse". Nineteenth-Century Art Worldwide 1 (2002).
- Tasos A. Gritsopoulos, "Το κρυφό σχολειό" Παρνασσός 4: 66-90 (1962).
- Tasos A. Gritsopoulos, "Το κρυφό σχολειό: παιδεία ελλήνων - οργάνωσις αυτής μετά την άλωσιν" Πελοποννασιακά 13:1-52 (1978–79).
- Hellinomnimon Project, "Greek Higher Schools (1620-1821)". University of Athens. [dead link]
- Christos G. Patrinelis, "Η διδασκαλία της γλώσσας στα σχολεία της Τουρκοκρατίας" ("Language [sc. Greek] teaching in schools of the Turkish period") in M. Z. Kopidakis (ed.), Ιστορία της Ελληνικης Γλώσσας (History of the Greek Language) Athens: Elliniko Logotechniko kai Istoriko Archeio. 216-217.
- Ioannis Polemism, "Το κρυφό σχολειό" Online text of the poem (in Greek)[not in citation given].
- ^ D. A. Zakythinos, The making of modern Greece: from Byzantium to independence Oxford: Blackwell, 1976. ISBN 0874717965