Staff strike over lost pay
Staff at Trentham, Holden Lane and St Peter's secondary schools walked out, claiming about 10 staff have been wrongly denied progression to upper pay spine 3 and a pound;1,100-a-year increase.
Around 2,600 children were kept off school by their parents because of the strike.
Chris Keates, general secretary of the NASUWT, said the dispute could escalate if the schools and local authority refuse to back down. Future action could include two or three-day walk-outs.
"It is with deep regret that NASUWT members have embarked on strike action.
However, all attempts to use other means to secure their pay entitlements have proved fruitless," she said.
"If there is no movement, then we could be looking at further action within a few weeks.
"The NASUWT has made it clear to the local authority and the schools that there is no need for this action to go ahead if they honour the terms of the national pay agreement."
A spokesman for Stoke-on-Trent council said: "We are sorry that the union would not accept our offer of taking the dispute to the independent arbitration service Acas which we believe would have been in the best interests of the children.
"We regret the disruption to children's education this action causes, together with the problems it creates for parents."