Innumeracy rampant: Student-teacher ratio and average class size

Innumeracy 1: Why the Student-Teacher ratio is not the Average Class Size.

The Toronto Star and the CBC constantly use “average class size” when reporting education news. For example, the Toronto Star recently reported that the Ontario Minister of Education was offering to reduce the average class size from 28 to 25. He did no such thing. He offered to reduce the student-teacher ratio, which is something quite different.

Here’s an example showing the difference, using the 28:1 ratio that the Ford government initially mandated.

Given: A high school of 1120 students.

At 28:1, this school will be assigned 1120/28, or 40 teachers.

Of these 40 teachers, one is a principal, one is a vice-principal, three are guidance counsellors (1).

Thus there are 35 teachers available for classroom teaching. A teacher is assigned 4 teaching periods in a 5-period day. Therefore at any given time, 28 teachers are in class, and 7 have a preparation period (2). This means that the average class size is 1120/28, which is 40 students per class, not 28. (3) (4).

The 22.5:1 ratio that existed prior or the Ford government’s changes came about because of attempts to keep average class sizes below 30. Even so, class sizes above 30 were common.

Footnotes:

(1) The Provincial average is 396 students per guidance counsellor. In larger schools, there will be two vice-principals.

(2) If an emergency absence occurs, a teacher may have to do a “standby” during a prep period.

(3) Special education classes are capped at 20 students. Safety regulations limit lab and shop classes, generally around 24. Some other classes (music, arts) are limited by the available space and supplies, generally also around 24. Thus, the remaining classes will be well above 40 students per class.

(4) Senior students may qualify for “spares”, but these days most opt for taking additional courses instead, so as to be better perpared for university or college.

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