You've seen it. A group of kids is at a corner. The light turns and an older person walks out holding up a big stop sign and stands in the middle of the street till they are all across. All traffic is supposed to be frozen during this interval. And it's not just kids, they have older ones, like sixth graders!
So when they get older and go to college, they carry with them this imaginary image of protection and just step off the curb, assuming that cars will look out for them. And most importantly, they assume the driver will make no mistake!
What I would have the crossing guard do is stand back and watch. And if a student looks like they're going to step off the curb wthout looking, the crossing guard would reach out with their ten foot shepherd's crook and pull the offender back, perhaps even down on their little fanny! This would make an impression that would last a lifetime! If they got a little pain or were embarrassed, it would be minor and certainly better than being hit by a moving vehicle.
This conjures up a picture for me of an athletic field with all kinds of crossing guards with crooks, praticing on dummies to make sure they are accurate and use just the right amount of force!