A group of teachers was on ERT TV shortly after 9 p.m. Saturday, interrupting the main news broadcast.
The newscaster suddenly announced, mid-report, that the broadcast was being interrupted for a commercial break.
When the newscaster returned from the break viewers saw her refer to another studio in the building where protesters were shouting slogans and were holding a huge banner demanding permanent jobs in state schools.
A representative read live on TV their demands for about three minutes.
On Friday, teachers rallied outside Parliament and clashed with police, who responded with tear gas.