There’s a picture from my first day of school, fourth grade, that explains exactly why I got beat up. I’m wearing a brown plaid sweater; I have glasses, which no one had in fourth grade except kids who thought they were smarter than everyone else, and a briefcase.

A red flag to a grade school bully: “Oh, look at Mr. — uh, Mr. Briefcase, with his briefcase and everything. What you got in there? A picture of Mommy? I bet you got a picture of Mommy in there. Does your Mommy have a briefcase?"

“No. All I have are pencils and a Tom Swift book. I don’t have a picture of my mom.”

“Why, because she’s too ugly?”

And so on, with inexorable bully logic. I don’t remember the exact sequence of events, but the bully — who had marked me as Plump Dork Target, easy work — eventually knocked me down. And he was on crutches. There is no humiliation like holding up your briefcase as a shield while a kid leans on one crutch and hits you with the other. Yes, girls, I’m available!

For many, the first day of school has a little greasy squirt of doubt in the gut, wondering if you’ll sit next to Your Nemesis. To my relief, he was on the row up front by the door, which made it easy for the teacher to point to the exit he would take to go to the principal’s office.

The reason this event stuck in my memory? Aside from the pain and shame — not to mention the desire to seek revenge in some forum like a newspaper column someday that stops short of naming him because of libel laws? Because my mom always took a picture of me on the first day of school.

I do that for Daughter, too. Kindergarten: a brave kid with a bowl cut, ready for the world. Ready for the bus. Second grade: saucy expression, because she knew the drill, had it cold. Middle school: practiced smile hiding trepidation. High school: Must we?

The last year of high school: Glad this is the last time we’ll do this, gah. Yes, yes, there’s tradition, but c’mon.

You can print them out and make a 12-frame flip book in which it takes a second and a half for them to grow up to the point where they’re ready to fly.

Snap — like that.

So you make them stand in the same place and take the same picture, and you wonder if 30 years from now, they’ll look at an image and think, “I remember that backpack. I loved that one.”

I loved my briefcase, even if it set off the bully. Sure, he beat me up, but I’ll bet his arm was sore the next day. Ha! Served you right, John Lar —

Oh, right. Libel laws.