Schools are facing disruption as members of the biggest teaching union are set to strike on Wednesday.
The National Union of Teachers (NUT), which has between 800 and 1,000 members in Colchester, Clacton and Harwich, has called for a walk-out over workload, pay and pensions and the need for every classroom to have a qualified teacher.
It is the third strike to be called after the union balloted for industrial action in 2011.
The Government has dubbed the strikes disruptive and damaging.
Jean Quinn, public relations officer for the Colchester and North East Essex NUT, said: “We deeply regret that it is disruptive to people but the purpose is to send a message to the Government and we hope parents will support us as they too will want a qualified teacher in front of their children."
A Department for Education spokesman said: "Parents will struggle to understand why the NUT is pressing ahead with strikes over the Government's measures to let heads pay good teachers more.
"They called for talks to avoid industrial action, we agreed to their request, and talks have been taking place weekly.
"Despite this constructive engagement with their concerns, the NUT is taking action that will disrupt parents' lives, hold back children's education and damage the reputation of the profession.”