More than 300 classes are being cancelled over the coming school year and another 300 or so will continue on with larger class sizes as a result of provincial changes to class size averages, the Toronto District School Board says.

News of the cancellations came Friday afternoon from TDSB spokesperson Ryan Bird, who provided a list of courses affected by the changes.

"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," Bird said in a statement.

Owing to the changes, he said, a number of elective courses are being cancelled, others will continue with larger class sizes or combined grades, and library and guidance services will also see reductions.

Among the classes affected by larger sizes and combined grades are:

123 Grade 9 compulsory courses (including English, Math, Science, Geography, French and Phys Ed.).

64 Grade 10 compulsory courses (including English, Math, Science, History, Civics and Career Studies).

133 Grade 9/10 electives.

414 Grade 11/12 electives.

Where compulsory courses are affected, the board says, the remaining sections will see larger class sizes.

Reductions to staffing will not only have an impact on course selection, said Bird, but will also mean fewer supports for students who need them.

As part of the Ford government's changes to Ontario's education system in March, average class sizes were expected to go up from 22 to 28 for Grades 9 to 12.

The board estimates that beginning in the 2019/2020 school year, class sizes will rise by an average of 1.9 for the first year to 23.6. students per class.