Anyone who tried to navigate the Main/Winchester/Marlboro Street roundabout in Keene at certain times this past week could tell you that Keene State College is back in session.

And so it is for elementary and secondary school students this week. Schools start today in Fall Mountain and Hinsdale; Wednesday in Keene and the Unit 29 towns, ConVal, Jaffrey-Rindge, Monadnock and Stoddard.

The de facto end of summer always seems to sneak up on us. The warm, humid weather is typically still in full bloom at the end of August. Heck, Labor Day cookouts haven’t even happened yet. But the bus schedules for several districts ran in The Weekend Sentinel days ago, so it must be true.

Back to school means a big change for many people. It means children’s weekdays are spoken for, which is a change for them, but also for parents, who must adapt to a new routine. Teachers have been getting ready for weeks, but that’s not the same as facing down a classroom full of eager — and some less-than-eager — learners. It means changing routines for stores and restaurants, as some young employees become unavailable and families reevaluate their meal and shopping schedules.

It may be especially jarring, though, for local drivers, who will suddenly find themselves following school buses that stop frequently and coming upon crosswalks filled with children and/or crossing guards.

They’ll also find more children riding bicycles, on skateboards or scooters, and afoot in other places. In the mornings, some of these children may be hurrying to reach school or buses on time, or may have just woken up. After school, the danger is multiplied. The American Automobile Association says that, over the past decade, nearly one in four pedestrian fatalities involving children occurred between 3 and 7 p.m.

Drivers need to pay attention to these dangers, and heed both the directions of crossing guards and the laws regarding school-zone speed limits and not passing stopped school buses.

And, we can’t think of a better time or more compelling reason to remind motorists to keep their hands on the wheel and off their cellphones.

Of course, safety awareness cuts both ways. Not only should drivers be paying greater attention — all year, really, but more than ever in these crucial few weeks during which everyone is preoccupied and getting used to a new schedule — parents should be making sure their children know to stay visible, cross only at crosswalks, look both ways, lose the headphones and, if they might be out after sundown, wear reflective clothing or bring a flashlight.

Consider it the first lesson of this school year.