WA's teacher union has rejected a second pay and conditions offer from the state government, stoking concerns of interruptions at public schools as the union threatens to forge on with a potential strike.

The state government has offered a 5 per cent pay increase, followed by two years of 3 per cent pay rises, totalling 11 per cent over three years.

The State School Teachers' Union of WA (SSTUWA) has asked for 7 per cent followed by 5 per cent, totalling 12 per cent over two years.

The union has also demanded a range of measures to improve workplace conditions and address teachers' workloads.

Among the demands are restrictions on class sizes, which SSTUWA President Matt Jarman said are the "biggest in WA compared to anywhere else in the country".

"We have extraordinary pressures on teachers and school leaders and they are spending an enormous amount of their life at work," he said.

"To a degree, our members, through our executive, feel that the second offer is a little bit on the insulting side."

Mr Jarman said there was a "crisis" in the public school sector.

"Teachers and school leaders have accepted four years of wage freezes while the cost of living has been skyrocketing.

"Our members are facing significant workload issues, which have not been adequately addressed in the government's second offer," he said.

First-year teachers earn an annual salary of $78,397 and senior teachers with at least a decade of experience earn $117,854.

The state government repealed its blanket public sector wages policy in December.

Mr Jarman said he expects "thousands" of teachers to take part in a half-day stop-work action on April 23 if an agreement isn't reached.

"Our website crashed on Friday when we released information to do with the stop-work action, we had 400 members a minute trying to access that information," he said.

'Hope' strike will be averted: minister

Education Minister Tony Buti said he was hopeful an agreement could be reached before the union forges ahead with a planned half-day strike next Tuesday, April 23.

"I hope it will be averted. We continue to bargain in good faith," he said.

Mr Buti said the Department of Education was making arrangements for the potential strike.

"This is being worked through, it's a half-day strike, the Education Department is working through that process," he said.

The state government said it was working to avoid any disruption to schools and families.

"However in the event industrial action does proceed the Department of Education is preparing to minimise the impact on students and parents," a spokesperson said in a statement.

Payments for families rolled out

The union's rejection of the enterprise bargaining agreement comes as students begin their second term of school.

An estimated 300,000 WA families are eligible for the state government's cost-of-living relief package, which rolled out today.

A one-off $250 payment is available for each secondary school student, and $150 for each primary and kindergarten student.

The union has welcomed the relief for families, but has urged the state government to focus its budget on improving public schools.

"What I would say to the treasurer, and to the premier, is share the [state's budget] surplus," Mr Jarman said.

"The public education system is in crisis and parents understand that.

"It's now time to fix public education."