I attended two presentations last week at my daughter’s Upper West Side elementary school. The first featured the chancellor in charge of New York City schools, who was on hand to absorb parents’ rage after a paraprofessional at the school was arrested on suspicion of sexual misconduct with a young boy.

Talking to an overflow crowd, Chancellor Dennis Walcott said what you’d expect him to say: The safety of children is his top priority, and steps will be taken to make sure incidents like this never happen again. But less than a week later, a teacher at an elementary school in Queens was arrested on suspicion he inappropriately touched young boys.

Both incidents occurred just weeks after the arrest of a teacher’s aide at an elementary school in Brooklyn. Investigators say the aide possessed child pornography and may have created a sexually explicit video at the school.

The presentation by the chancellor allowed parents to vent their rage over what they see as weak administrative controls. But I’m afraid I agree with Mayor Mike Bloomberg’s fatalistic attitude that no amount of prevention will entirely eliminate evil intent. “The school system’s got something like 125,000 people, and I don’t think it’s practical to think there isn’t going to be somebody doing despicable things,” Bloomberg said. “There are some sick people in the world, and you just have to learn to deal with them.”

The second presentation I attended was an evening workshop to explain the anti-bullying program being taught in my daughter’s school. The idea was to give parents the necessary background and vocabulary (in particular the precise definition of “bullies,” “targets” and “bystanders”) so that parents could reinforce the lessons at home.

This bullying meeting drew a fraction of the parents who showed up to hear the chancellor, and that’s a shame. I left the chancellor’s meeting feeling powerless, but I left the second meeting equipped with useful tools that will help me guide my daughter through the rocky obstacles that are part of life in a New York public school.

And in many ways the anti-bullying message contained the seeds of wisdom I need to keep my daughter safe from both bullies and sexual predators. One solution is to teach children not to be passive victims if they become targets, and to not be silent bystanders if they are witnesses. Children rarely learn these skills on their own. They need parents willing to talk to them about uncomfortable topics, even when broaching such topics chips away at the innocence of childhood.

There are few heroes amid all these arrests and allegations, but I know of one. A man accused of an evil act is sitting in jail rather than working in a classroom, and it’s largely because one young child knew enough to speak up and tell someone in authority that something was wrong. That brave child is to be commended, along with the wise parents who raised him.

I plan to soon teach my own child this vital skill. Fortunately, I’ve received help from “Say No! Protecting Children Against Sexual Abuse,” also known as Publication 1154 from the state’s Office of Children & Family Services. It’s seven concise pages of tips and talking points designed to help parents discuss a difficult and sensitive topic with young children.

I knew someday my little girl would learn that the world isn’t always a good, safe place. I just didn’t realize I’d have to be the one to break the bad news.