This Ontario election campaign features a familiar theme—political leaders, regardless of party, proposing simple solutions to very complex problems. And in education, what could be simpler than reducing class sizes? With smaller classes, students get more individual attention from their teachers and teacher workloads become more manageable. At first glance, this looks like a win-win solution.

Perhaps this is why Ontario Liberal Leader Steven Del Duca has pledged to impose a hard cap of 20 students on all classrooms at all grade levels, and to achieve this goal, hire 10,000 new teachers.

Del Duca is far from the first Canadian politician to push for class size caps (although he might be the first to suggest imposing it on all grades and subject areas). Smaller classes are easy to explain to parents and the less time political leaders spend explaining the specifics of their policies, the better things tend to go for them.

However, no policy exists in a vacuum. Costs must be considered. Assuming that the total salary and benefits of each newly hired teacher is only $50,000 (a ridiculously low assumption), the province must increase its education budget by at least $500 million per year just in teacher salaries. And this would not include the cost of any new infrastructure such as an increase in the number of classrooms needed, nor would it account for already-negotiated annual salary increases of existing teachers.

In other words, capping class sizes is a prohibitively expensive proposition for a province already heavily indebted. If the Ontario government goes ahead with this hard cap, it almost certainly won’t have money to spend on anything else related to education. In other words, for capping class sizes to be good policy, it must have a dramatic and positive impact on student academic achievement.

Unfortunately, that’s not what the research shows. In 2019, Derek Allison, noted education scholar and professor emeritus at the University of Western Ontario, conducted an extensive review of education research on the impact of smaller classes on student achievement. Allison found that while smaller class sizes at earlier grades were moderately beneficial, class size had no impact on student achievement in upper grade levels.

Furthermore, students in provinces with smaller class sizes at the secondary level do not outperform students in provinces with larger class sizes on the Programme for International Assessment (PISA) tests. In fact, the reverse is true. Higher-performing provinces such as Quebec and Alberta actually have larger class sizes at the secondary level than lower-performing provinces such as Manitoba and Saskatchewan.

Clearly, smaller classes are not the panacea some politicians and teacher unions claim.

In addition, we should recognize the logistical challenges that arise from hard class size caps. While classes might end up being a little smaller, many schools will be forced to create split classes. For example, a small school with 22 Grade 5 students and 18 Grade 6 students will have no choice but to put students into two Grade 5/6 classes of 19 students each. Most parents and educators understand that it makes far more sense to keep students in single grades together.

Not only that, but a hard class size cap would force high schools to cap enrolment in important electives. Clearly, it would be far better to have a single Chemistry class with 23 students than to artificially cap the number at 20 and leave three students on the sidelines.

If we want to see improved student achievement, we must focus on things that actually matter—namely updating curriculum and improving instruction. Good teaching is good teaching, whether it takes place in a class with 20 students or a class of 30 students. Given the choice of being in a class of 20 taught by a mediocre teacher or a class of 30 taught by an outstanding teacher, most students and parents would choose the latter.

Updating the curriculum and improving the quality of instruction in Ontario might not fit easily into a political soundbite, but it’s a much more sensible direction to go. Capping class sizes sounds good in theory, but it will do little in reality.