Annual snow fall moderates the relationship between daily snow fall and the likelihood of canceling school

Moderation isn't one of those things that we typically teach in Intro Stats.

But it is a statistical tool your advanced undergraduates will likely encounter in an upper-level course.

I'm not going to teach you how to teach your students how to do one. I am, however, going to share a  example of what mediation is doing, inspired by living in the city in the US that has received the most snow this season (Erie, PA, with 93.9 inches for the season as of 1.30.25). 

About a year ago, CNN shared data on how much snow it takes to cancel school in various parts of the country.

I assure you, Erie and the rest of Northwest PA (see red outline) gets hella snow but no snow days.

https://www.cnn.com/2024/02/12/us/how-much-snow-kids-school-snow-day-across-us-dg/index.html

However, our lack of snow days isn't due to lack of snow. The annual amount of snow moderates the likelihood to cancel school, such that if you are used to a lot of snow (and have the infrastructure to handle it) you don't cancel due to snow. And as much as people in snowy regions like to dismiss concerns about snowy roads and safety, the fact is that it isn't a mindset that leads to these choices, it is the preparedness to deal with snow. And I bet the amount of snow a region experiences correlates with the State and Local DOT funding for plows. This is illustrated nicely below. For further reference, I live about an hour west of Chautauqua, NY. 

To make this simple, and use the oft-imitated visual representation of moderation: