Greece is trying to send the children of migrants to Greek schools. There has been resistance from Greek parents out of various fears, including fear of sicknesses and differing cultures. Local governments have been vocal against the Greek parents.
Ultimately, the rights of the Greeks have been subordinated to the rights of illegal migrant invaders. If those migrant children have to be educated, I don't see why that can't be done at the camps. Learning Greek (if they are even interested), Math and English or another European language of the country where they want to go to does not require integration in regular Greek schools.
Until their asylum requests in Greece have been accepted, Greece has no obligation towards them. These are people just waiting to go to rich European countries, they bring nothing to Greece but misery.
Greeks often say that their ancestors were refugees too. The difference is that when the Greeks came from Anatolia, they were Greeks going back to their motherland, they were not illegal invaders.