TORONTO -- The Toronto District School Board has pushed back the start date for elementary school students who are attending classes virtually this fall.

In an update posted on the school board's website on Thursday night, the TDSB confirmed that students enrolled at virtual schools will begin classes on Sept. 17, two days later than initially planned.

"Due to the large number of families who have selected Virtual School (more than 66,000 students), we require additional time to staff and timetable to ensure a more consistent opening for all staff and students," the TDSB's statement to parents read.

"As a result, all students, including those in Special Education classes, attending Virtual School... will begin on Thursday, September 17."

In-person learning at elementary schools will proceed as scheduled with a staggered start to classes beginning on Sept. 15, the board confirmed Thursday.

The decision to push back virtual learning for elementary students comes just one day after the school board delayed the start of high school classes, both in person and virtual, by two days.

The TDSB attributed the delay to challenges with the "secondary staffing and timetable process."

All secondary students at TDSB schools will now begin the school year on Sept. 17.

"Our top priority is to ensure students experience success in both our in-person schools and virtual schools," the TDSB said.

The school board warned that there could be some hiccups as students and staff adjust to the new protocols.

"While we have been working diligently to prepare to safely reopen the system in this new reality, there will be a period of adjustment while everyone learns and adapts to the new protocols and practices in place and reconnects after being away for several months," the TDSB's statement read.

"We are committed to working together through this phase of reopening and will make any necessary adjustments along the way. We ask for and appreciate your patience during this transitional time and remind everyone that the health and safety of staff and students continues to be our priority."

The TDSB also said it has heard from "a number of parents" who have concerns about elementary class sizes and the board remains "committed to achieving class sizes that do not significantly exceed our targeted caps."

"We are looking at strategies to address situations where the in-person enrolment is higher than we anticipated," the board's statement read.

"As the numbers continue to change, please note that any necessary adjustments may not be in place on the first day of school, but we will be working to rectify these situations as quickly as possible."

Classes have already begun for some students at GTA schools outside of Toronto.

Boards in the regions of Peel, York, Halton, and Durham began a staggered start to school year earlier this week.

Classes at the Toronto Catholic District School Board will resume next week.