WASHINGTON — I went to work with my wife last week, something I should have done years ago. But as a practiced procrastinator, I never got around to it. I was curious to see how she does what she does. I was also conscious of a paradox. Although nearly four decades of writing newspaper and magazine columns have given me a modest public profile, I am certain that Judy does more public good in a week than I’ve done in a lifetime. She teaches first grade.

If you think teaching is a cushy job, think again. Done properly, it’s grueling. A recent nonscientific survey of 30,000 teachers by the American Federation of Teachers found that nearly 80 percent “are often physically and emotionally exhausted at the end of the day.”

No kidding. We wake before 6 a.m. so Judy can get to school early and prepare her classroom. After school, she stays until nearly 6 attending teachers’ conferences, calling parents and preparing for the next day. Once we finish dinner, she’s correcting papers and planning. Over the years, weekends often included trips to students’ baseball, soccer and basketball games. All this occurred even when our now-grown children were in the house.

Among America’s 3.5 million elementary and secondary-school teachers, I doubt many are more devoted and more competent than Judy. But I suspect that there are tens and tens of thousands who are just as devoted and just as competent. Their qualifications seem to include three imperatives.

First, you must like kids. If you don’t, you won’t be motivated to do all the other necessary work — and to put up with inevitable setbacks and frustrations. On this count, Judy has no problem. The day I attended, one little boy rushed into the classroom and spontaneously hugged her.

Second, you’ve got to master the subject matter. You can’t teach what you don’t know. The students will sense it, undermining your authority.

Finally, you need a teaching style that engages the kids while also promoting a classroom atmosphere that’s both loose and disciplined.

At the year’s start, Judy said her overriding goal was “to make kids like school.” By that, she didn’t mean that the demands would be so lax that the students would have a false (and ultimately ruinous) sense of accomplishment. Just the opposite: They would understand how hard work leads to new skills and vistas. Her motto is: “Teach up [in expectations]; teach to the child, not the curriculum.”

Her classroom style, I see, is a seamless mix of rewards and limits. She played an oral math game; every student who answered correctly got a “knuckle bump” from the teacher. By contrast, when students wandered off task, they were quickly reminded to return to work. If they didn’t, consequences followed.

However, teachers are not miracle workers. A few years ago, Judy had an exceptionally disruptive student. He should have been removed from the class; he wasn’t. She spent an inordinate amount of time influencing and corralling his behavior, and although she had some success, the effort detracted from working with other students. They suffered.

Likewise, schools can’t easily compensate for social problems beyond their making. Judy’s has had students from all economic classes, but for the past three years, she has taught in a school with a low-income population that’s about 90 percent Latino. From my brief observation, these are really sweet kids. But many face special burdens: fractured families; parents who don’t speak English and are sometime illiterate in Spanish; parents with crazy work schedules. There’s a larger issue, as a recent report from the left-leaning Economic Policy Institute warned:

“Lower-social-class parents engage in fewer educationally supportive activities with young children, such as reading aloud or playing cognitively stimulating games.”

Although Judy is past the standard retirement age, she looks and acts 10 years younger. Still, she’s decided to retire now. I regret this, partly for selfish reasons: She’s planning all sorts of post-retirement projects that are supposed to (but don’t) inspire my enthusiasm. But my main regret lies elsewhere. It is that the prospects for America’s children will be a tiny bit worse because she’s no longer in the classroom.

On the last day of school, a student gave her a card. It said: “Thank you for working with me this year. God bless you! I love you. You are the best teacher in the world.”

Robert Samuelson is a columnist for The Washington Post.