Make classes smaller. This is one of the most common demands made by teacher unions. The Alberta Teachers’ Association (ATA) recently released a set of policy proposals and, unsurprisingly, reducing class sizes is at the top of its list.

It’s understandable. All other things being equal, smaller classes are easier to manage than larger classes. Fewer students means less marking, fewer behaviour problems and more time to work on other things. Any union worth its salt will push for reforms that make its members’ lives easier and this one certainly fits the bill.

Reducing class sizes is also popular with the public. Opinion polls show that parents prefer having their children in smaller classes. Given the amount of support for smaller classes, it’s strategically smart for unions to put this demand front and centre. This way teacher unions look like they are selflessly advocating for students.

However, research by Derek Allison, professor emeritus at the University of Western Ontario, reveals that while there are some benefits from smaller classes in early grades, these benefits are limited. As for high school, there’s no correlation between smaller classes and student achievement. In other words, we should not expect smaller classes to produce better performance, particularly at the high school level.

Allison is far from the only researcher to come to this conclusion. John Hattie, director of the Melbourne Educational Research Institute at the University of Melbourne (Australia), has analyzed thousands of studies on student achievement and found “there is a voluminous literature that does not support the claim that learning outcomes are enhanced when class sizes are reduced.” Hattie believes this is mainly because teachers tend to use the same teaching methods with small classes as they do with large classes.

Moreover, reducing class sizes is one of the costliest education reforms a government could implement because it necessitates hiring more teachers, and teacher salaries are by far the largest part of a school board’s budget. It should come as little surprise that one of ATA’s other demands is to hire approximately 4,000 additional teachers. If we assume that each teacher costs approximately $80,000 (salaries and benefits included), this amounts to an extra $320 million each year, a rather large sum indeed.

Of course, this number doesn’t include the cost of building extra classrooms and portables to house these additional teachers. Nor does it consider the fact that school boards would need to be less selective in their hiring decisions. Mediocre teachers who would ordinarily be passed over by school boards might soon find themselves gainfully employed. Students unfortunate enough to be in their classrooms would end up suffering the consequences.

As a case in point, when the state of California implemented a K-3 class-size reduction program in 1996, it created approximately 25,000 new teaching positions, many of which were filled by inexperienced or uncertified teachers. A study by researchers Christopher Jepsen and Steven Rivkin published in the Journal of Human Resources found that the positive benefits from these smaller classes were largely offset by the negative effects of placing students with less-qualified teachers. In the end, California spent a huge amount of money for a negligible gain.

It's also important to remember that teacher unions have a vested interest in this issue. Not only do smaller classes improve the working conditions of their members, they also lead to the hiring of more teachers who all became dues-paying union members. Thus, the unions get to increase their budgets while appearing to advocate for the public interest.

Finally, consider the opportunity cost of smaller class sizes. Any province that makes reducing class sizes a top priority will almost certainly have no money for anything else. Money that could be spent on improving the curriculum, purchasing updated textbooks, investing in technology, repairing school buildings and developing better standardized tests would instead be used to hire a glut of additional teachers, many of whom will be mediocre at best. This would be a poor policy decision for any government.

Giving in to the pricey demands of teacher unions might fill union coffers, but it certainly won’t fix public education.