Open this photo in gallery Ontario Education Minister Lisa Thompson at the Ontario Legislature in Toronto on July 30, 2018. Chris Young/THE CANADIAN PRESS

The Toronto District School Board will be cancelling more than 300 courses in its high schools in the next academic year as a result of provincial changes to class sizes.

The school board on Friday released a school-by-school analysis of both elective and compulsory courses that will be cancelled or scaled back, as well as those continuing with larger classes and combined grades.

The 313 cancelled course sections include classes in English, geography, economics and science. The board said secondary schools will offer all compulsory courses required for graduation, but there may be fewer time slots when they are offered and the classes would be larger.

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“We’ve said from the beginning that when you reduce the number of secondary teachers in our schools, it has a direct impact on the course options and services for our students,” spokesman Ryan Bird said in an e-mailed statement.

"As a result of provincial changes to class-size averages, we’ve seen a number of elective courses cancelled, a number of others that will continue but with larger class sizes or combined grades and levels and a number of other services such as library and guidance reduced.”

In total, more than 700 secondary school courses are affected by changes to class sizes, the TDSB noted.

Doug Ford’s government announced earlier this year that it would increase average class sizes by one student in Grades 4 to 8, and to 28 from 22 in high school over the next four years – eliminating an estimated 3,475 teaching positions as it tries to trim a deficit it pegs at $11.7-billion.

Education Minister Lisa Thompson said no teacher would lose his or her job despite the changes, meaning that teaching positions would not be filled as educators retire or voluntarily leave the profession.

But several school districts have warned that changes in class-size averages will result in fewer course options for students, especially specialized classes, and could ultimately affect graduation rates.

A spokeswoman for Ms. Thompson said on Friday that the government is providing boards with $1.6-billion in transitional funding, and that should be used to protect specialized programs.

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“School boards simply do not have the information they need to be able to communicate these changes. The TDSB is acting irresponsibly and only scaring students and their families," Kayla Iafelice said.

She said that school boards should have more information to plan for the next school year before the end of the month.

The TDSB said its average high-school class size would rise to 23.6 from 22 in the next school year, as it moves toward a class size average of 28 over four years.

The board has estimated that the changes would result in the loss of about 800 teaching positions.

It said on Friday that a staffing reduction would also affect supports for secondary school students, including fewer teacher librarians and guidance counsellors.

Leslie Wolfe, president of the Ontario Secondary School Teachers’ Federation Toronto, said her union has been worried about students losing out on program choice as a result of the government’s cuts. “It is only going to get worse in each successive year,” she said.