The best time to think about how you’ll tackle difficult subjects with your children is before the need arises.

I was reminded of this by Melissa Schorr’s recent article on her “protective instincts” in The Boston Globe Magazine. Her daughters (one 8 years old, the other younger) “haven’t been told about September 11. Or the Sandy Hook shootings, which happened to occur the week we were at Disney World. Or about real-life monsters, like Ariel Castro.”

So when her third-grader came home to report that she’d chosen a book about Anne Frank from her classroom shelves, Schorr (a regular contributor to The Globe and a young-adult author) found herself “for the first time on the other side, able to sympathize with those parents, the ones who try to yank books from public libraries and harass school librarians for what they deem inappropriate for their precious snowflakes.”

She finds and reads the book herself, and it does not sugarcoat Anne Frank’s life or death or the events that engulfed her. She writes:

“As I close the book, I feel a wash of emotions: sadness, that my daughter has to learn of true evil in this world, directed squarely at her and her ancestors. Anger, that the choice of how and when to tell her has been stolen from me.”

I should probably say that although I don’t dwell on tragedy, Schorr’s way is not mine; we had a carpool conversation last week, over whether the government should seek the death penalty in the Boston Marathon bombing, that included my 7- and 8-year-olds as well as my older children.

But the last line of that paragraph struck me just the same: “the choice of how and when to tell her has been stolen from me.”

Every time there is a national tragedy or a big anniversary, how we talk to our children about it (or how we shouldn’t) becomes a topic, and the question of how and when to talk with your children about lynchings, racism, the Holocaust, internment camps and the rest of the worst moments of our recent past is a perennial parent dilemma.

The “choice of how and when to tell” is a luxury we should appreciate and seize.

Why ruin a beautiful day with talk of horrors? Because we’re lucky enough to have the beautiful day to put some distance between our conversation and ourselves.

If you take opportunities to talk to your children about difficult topics when they arise, then when circumstances push those conversations on you, they flow more easily.

I never set out to explain prostitution in the hockey rink parking lot (thank you, Public Radio International’s “The World”), segregation en route to Vermont or sex abuse on the sidewalk between the bookstore and the diner (or, for that matter, menstruation in the “feminine hygiene” aisle at CVS), but that’s when those things came up, on the radio or because of something else we saw or some question that was asked, and I went for it.

Rhonda Fink-Whitman’s video of Pennsylvania public school graduates who were unable to answer the most basic questions about the Holocaust prompted me to sit down with my older children (first, to ensure that they knew the history, and second, to tell them directly that if someone points a video camera at you and says, “Can I ask you a few questions,” the right answer in the YouTube age is no).

For the younger children, the topic came up at dinner – during a conversation that somehow veered off the usual topics of school, friends, manners and plans onto race and slavery.

When your children ask questions, or the headlines blare, it’s tempting to sidestep, or to turn away and wait for a better time.

Sometimes that’s appropriate, but if the better time never comes, then ultimately the choice of how to talk about an issue will be made by others, and the choice of when to talk will be made by circumstance.

If you want to decide how your children hear about school shootings, Jerry Sandusky or anything else, pick a day, seize a moment and begin.

IF PRESCHOOL is having a moment, it is due in part to its appeal to voters as a program designed to help children: preschool is “the most cost-effective” educational intervention, one that can set children up for greater success not just in reading and math, but in their social and emotional development.

Any parent who has raised children in a truly diverse environment has had occasion to grieve how the lives of toddlers who once shared a park sandbox can diverge so dramatically as they grow older.

Making preschool available to more children feels like an effort to level that particular playing field.

Preschool’s benefits, though, extend beyond the young students to their parents and families. Many programs, like Head Start, have a focus on family outreach, both with the goal of helping parents to help their children, and with the intent of helping the parents to establish more stable and secure lives for themselves and their families.

Parents who are part of a strong public preschool program may find support there for applying for housing assistance or returning to school.

When public education starts earlier, parents at all income levels benefit. The expensive burden of day care is lifted sooner.

Even for families who can afford to have one parent remain at home, preschool can place structure on a day; it can allow an overwhelmed parent time to breathe or encourage parents whose choice to remain at home was constrained by the economics of child care to return to work sooner, with less time and income lost to years at home.

Contact KJ Dell-Antonia at: kj.dellantonia@nytimes.com