Nearly 200 schools in South Australia (SA) have closed, with hundreds of the state's teachers going on a half-day strike.

Parents were forced to make alternative arrangements on Thursday morning when about 183 of SA's 875 public schools and pre-schools closed their doors to students as staff rally in Adelaide's Central Business District (CBD) to demand better pay, smaller classes and extra sick leave.

Of the schools that remained open, about 194 ran a modified learning program to cope with staff shortages caused by the strike.

By comparison, nearly half the schools in the state were shut down when the Australian Education Union (AEU) went on strike in SA in 2008.

"Let there be no mistake, this is a resounding vote of no confidence in the union bosses whose ill-conceived rush to strike has been shown to be puerile in the extreme," Rob Lucas, the Treasurer of SA, told reporters on Wednesday night.

"They've shown poor judgment and complete lack of regard for hardworking parents and grandparents in their race to industrial action," Lucas said.

In a letter to Lucas and John Gardner, the state's Education Minister in October, AEU SA President Howard Spreadbury called for an immediate 3.5 percent "interim salary increase" while the parties continued to work on a wider enterprise bargaining agreement.