© Brittany EvinsTeachers rally outside the Education Department building in Flinders Street.
Flinders Street has been blocked off to all traffic, with protesters making their way to the rally from all corners of the city.
Signs stating "Try Harder Gardner" and "More Funding For Our Kids" were being waved to loud music.
Police are monitoring traffic conditions and pedestrian movements.
School is set to resume at 12:15pm at the 192 schools that are closed.
Australian Education Union (AEU) SA president Howard Spreadbury said he was very happy with the number of teachers who joined the rally.
"I'm very pleased with the massive turnout of our members and community supports sending a very clear and definite message to the Marshall Government that they need to take us seriously and start listening to what we're putting [to] them in relation to our members' conditions and the learning environments of our students," Mr Spreadbury said.
Salisbury High School teacher Adrian Mann said the State Government was focused on putting money into school infrastructure rather than programs for vulnerable students.
"I just really want to see some more equality in terms of what we're able to do in terms of actioning resources," Mr Mann said.
"There's been a lot talked about resourcing by those in Government but much of it seems to be about infrastructure and it's all about what affects students in the classroom.
Contract teacher Teresa Tsouvallas said teachers wanted more permanency.
"It just makes our future a lot more unsure and we really need teachers that are enthusiastic to stay around and actually have a permanent job and a future in our schooling system," she said.
Treasurer downplays effect on students
Treasurer Rob Lucas told ABC Radio Adelaide this morning there were still about 700 schools open either running as normal or offering "modified programs".
"The Government - the taxpayers - are putting in an extra $200 million into schools this year and eventually there will be an extra $500 million," Mr Lucas said.
"Every other department and agency in the state is facing efficiency dividends and budget savings.
"Because of the priority we have given education, is there is a massive increase in education spending so any claim from [AEU SA president] Howard [Spreadbury] and the other union bosses is there are cuts to programs or cuts to funding is a nonsense."
Mr Spreadbury said the union's campaign had the backing of most teachers.
"A lot of those sites [that remain open] are not schools, they're preschools," he said.
"While a number of schools will be closed, a number of other schools will be running modified programs because they'll have skeleton staff because many of our members in those sites will be participating in the stop work action in the morning."
Mr Lucas said the Government would not be changing its focus on improving literacy in schools.
Mr Spreadbury said more industrial action could be ahead.
"If in fact we don't get a resolution out of this next little round of bargaining time then our executive will consider further action," he said.
The two parties will meet this afternoon.
Rallies are also being held in regional centres including Port Lincoln, Mount Gambier and Renmark.
Comment: It's the same story all over the Western world and people are beginning to get angry: