Joyous squeals mixed with heart-rending sobs March 31 as I fetched my daughter from kindergarten. Eighth-graders from a nearby middle school had just received letters informing them what New York high school they would attend, and sidewalks were jammed with clusters of anxious students ripping open envelopes that would reveal their futures.

New York can be a rough place for kids, but no day packs more joy and dejection than the moment high school assignments are announced. Dreams were dying. Friends were being ripped apart. The city’s method for assigning high schools has its defenders, but few believe this system is kind to 13-year-olds.

My 5-year-old daughter couldn’t ignore the cheers and tears, so I hurriedly looked for a way to turn the scene into what modern parents call a “teachable moment.” I told her the kids who were happy had done their best and won admission to a good high school. “The ones who are sad didn’t always do their best, so they didn’t get into the school they wanted,” I said. “Right now, they are probably wishing they had worked harder and studied more.”<!--more-->

When I related this explanation to my wife, she was horrified. “Plenty of kids did do their best and yet still didn’t get into their first-choice school,” she argued. Doing your best does not guarantee success in New York, she said, and it was wrong to make a child believe such a lie.

As usual, my wife is correct. The city doesn't have enough great high schools for all its hardworking teens, just as it doesn't have enough high-achieving neighborhood elementaries for all incoming kindergarteners. But a more complex question is: What lesson should a 5-year-old take from eighth-graders’ joy and pain? And what does “Do your best” really mean?

My lesson seems to have been cribbed from Battle Hymn of the Tiger Mother, Amy Chua’s memoir of her ultra-demanding parenting style. In one notorious anecdote, Chua rejected the birthday cards presented by her young daughters because the hand-drawn cards didn’t display enough effort. Similarly, I once chided my daughter when a homework assignment (yes, NYC kindergartners have homework) was dashed off carelessly. “But I did my best,” she protested. No you didn’t, I replied. I’ve seen your best, and that’s not it.

Fact is, few if any of us do our best (Amy Chua notwithstanding), since the nebulous goal is virtually unattainable. The admonishment “Do your best” is meant to signal a direction, not a destination. My teachable moment was not perfect (just ask my wife, or any parent of a heartbroken eighth-grader), but the message that we should strive to reach our full potential is worthwhile, at least for a kindergartner. Certainly the opposite holds true: If you don’t try to do your best, you will surely be disappointed with your high school.

Support for tough love comes from the Tiger Mother’s successful and happy daughter. In “Why I Love My Strict Chinese Mom,” Sophia Chua-Rubenfeld told her mother (via an open letter in the New York Post) that her strict, demanding upbringing didn’t leave scars, and the rejected birthday card is Exhibit A. “The card was feeble, and I was busted. It took me 30 seconds; I didn’t even sharpen the pencil,” she wrote. “If I actually tried my best at something, you’d never throw it back in my face.”

I’ll continue to urge my daughter to do great things, particularly in school. But in the future I’ll think twice before turning eighth-graders’ anguish into a teachable moment. I admit: On this one, I didn’t do my best.