Schools across Northern Ireland have resumed teaching after a half-day strike finished at noon on Tuesday.
The teachers took to picket lines over a dispute over pay and the future of the profession.
The NASUWT union said teachers were calling for a 12% increase in salaries.
Ian McGonigle, NEU NI president, said teachers are also striking for the future of the teaching profession and their colleagues.
"We all know teachers who are so burnt out they are going part-time in droves or on long term sick absence, colleagues at the beginning of their careers whose take-home pay will be irreparably damaged and reduce their earning power across their entire career," he said.
"For children without the SEN (special educational needs) support they need, or lost in the backlog waiting for assessment, for children whose education is at a detriment because of larger classroom sizes and less adults in the room, for the parents footing the bill because the school cannot afford basic supplies - we are taking this stand for them."
Meanwhile, the Education Authority (EA) said active engagement has been taking place for many months between management and the Teachers' Negotiating Committee (TNC) on a pay settlement for 2021/22 and 2022/23.
"However, it is important to note these negotiations are taking place at a time of growing and unprecedented financial pressures within the education sector which continue to adversely impact schools, staff and ultimately children and young people," an EA spokesperson said.
"Management side remains committed to continuing meaningful, active engagement with trade union colleagues to reach a resolution and ensure our teachers are fairly remunerated."
Schools reopened at midday on Tuesday and free school meals provided.
The Education Authority said guidance was issued to schools to help principals assess and prepare for any potential disruption.
It said those pupils unable to attend, while they would be marked absent, the strike would noted on their record as the reason behind the absence.
“Principals will have completed risk assessments and communicated any change of arrangements directly with parents via their own channels. Parents with any questions or concerns are advised to contact their child’s school directly.
“If a school is forced to close or partially close where there is industrial action, sessions for those pupils unable to attend are marked in the register using an appropriate code that will mean it is not counted as an unauthorised absence."
Principals were referred to the Department of Education's circular from August on managing absence. Should a pupil be absent because of staff industrial action it will be marked on their record with a '!'.
Tuesday also saw industrial action from some healthcare workers. Thousands descended on Belfast for a rally at city hall.
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