TORONTO -- Throngs of demonstrators covered the lawn in front of the Ontario legislature Saturday afternoon to protest the Progressive Conservative government's changes to the province's education system.

Many in the crowd carried signs declaring "Cuts hurt kids" or "Standing together for students," while others banged on drums or chanted slogans denouncing the government's measures.

The Tories under Premier Doug Ford have come under fire for recent changes including increasing class sizes, making students take more online courses and overhauling the province's autism program.

Sam Hammond, the head of the Elementary Teachers' Federation of Ontario, opened his speech with a call-and-response session with the boisterous crowd.

"Work with me here: If you're here to stand up for and fight for children with autism and their parents.... If you're here to protect publicly funded education.... Say 'I am!"' Hammond shouted to raucous cheers.

Hammond's union is one of five labour groups, representing education workers across Ontario, that organized Saturday's rally.

The ETFO said earlier in a statement that thousands of people were expected to attend and more than 170 buses were bringing teachers to the rally from as far away as Sudbury.

The event followed mass student walkouts that took place across Ontario on Thursday, which Education Minister Lisa Thompson characterized as "political stunts" encouraged by unions.

Hammond forcefully denied that claim on Saturday, saying the student activism on display showed the province's future is in good hands.

"Don't forget, Doug Ford: those students are going to be voting in the next provincial election. And we're voting with them!" he said.

In a statement Friday, Thompson said the government would not be distracted by what she called "union tactics" such as protests and rallies.

"The fact is that Ontario's teacher unions have been handed control of the education system for the past 15 years," Thompson said.

"Despite what unions say, their priority has not been student success and as a result our province's math scores are dropping and our students find themselves falling further and further behind."