Across Victoria, more than 44,100 children walked into the classroom for the first time, including 65 at Werribee Primary School.

Principal Lyn Tout said half of this year's prep group started on Monday and the others on Tuesday.

They will attend four days a week, with every Wednesday reserved for individual numeracy and literacy lessons with their teachers.

Ms Tout said the first day was spent familiarising the pupils with the important aspects of the school.

The youngsters got to know their teachers and fellow pupils, along with the location of the drinking taps, playground, library and where to go for their physical education classes.

"It's an exciting time for everybody," Ms Tout said.

"This is the start of 13 years of schooling for them, and our job is to prepare them for life, which is a great responsibility."

More than 540,600 children returned to government schools around the state this week.

As school began, Roads Minister and Tarneit MP Tim Pallas warned drivers to slow down and obey the 40kmh school speed zones. The zones apply from 8-9.30am and 2.30-4pm.

"Slowing down while passing a school is a small price to pay for saving the life of a child or sparing them from serious injury," he said.

"Research shows that even small reductions in speed have huge road-safety benefits.

"Parents should also ensure that when dropping off or picking up their children they obey all stopping restrictions, particularly near pedestrian crossings."