Most schools in Northern Ireland are said to be closed due to the industrial action.
The North Down MLA said: “When strike action was announced at the beginning of the month it will not have surprised anyone. We all know of the immeasurably impactful role teachers play in the lives of children and young people, but they are being undervalued and underpaid. The crucial work they do in our society should be recognised through a fair pay deal.
“We in Alliance have been supportive of the unions' recent campaign for fair pay in education because we need to ensure teachers are properly valued. Head teachers joining the strike action on this occasion highlights the significant pressure that they are under in managing extraordinarily tight budgets under severe financial pressure.
“It’s an unavoidable truth that the financial uncertainty they face is a direct consequence of having no Executive or local Education Minister to support our schools. A restored Executive would not solve every problem within our education system, but without the institutions back up and running, we’re at a complete standstill in dealing at all with the myriad of crises facing schools.
“Disappointingly, limited progress had been made in remedying the issues highlighted by teachers and school staff during widespread strike action back in February, and we urgently need a negotiated solution which reflects the important work of teachers and school leaders.
“The fact that the overwhelming majority of people dedicated to the education of our children feel they have no other choice but to strike should sound the alarm for everyone responsible for the governance of our education system.
“There are simply no excuses for the continued boycott of the institutions by the DUP. They are holding our entire education system to ransom, and it is totally unacceptable. With strike action by almost every teacher in Northern Ireland taking place today, it is time for the DUP to accept the fact that our children deserve better, end their deadlock, and get back to Stormont to get an Education Minister into office to deal with it.”