Slender Man: Do your kids know him, too?

NBC News national correspondent Kate Snow got quite a shock when she asked her 11-year-old about "Slender Man," the subject of her latest story. 

“I had a talk with my own son last night, thinking that he knew nothing about Slender Man. He knew all about it,” she said on TODAY. “I actually called some of his friends so that I could understand what this was.” 

After two 12-year-old girls in Wisconsin were arrested for allegedly stabbing another girl 19 times in order to curry favor with Slender Man, a ghoulish fictional character they had read about online, many parents like Snow are playing catch-up. 

Slender Man lurks in the edges of photos, a little off screen in videos; the tall, faceless man wears a black suit and in some images, black tentacles extend from his back. Since 2009, the myth has become so popular that one of its creators, Eric Knudsen, says that people search for historical evidence which they believe proves he actually exists.

But Slender Man is a crowd-sourced monster, a new urban legend, and entirely fake.

With adults falling prey to a myth like Slender Man, how do parents help their children understand the difference between fantasy and fiction online? And, how can parents know what their children are looking at online?

Relying on your children's friends to help fill you in is actually a great idea, says Michele Borba, parenting expert and a TODAY contributor, especially if your children respond to queries with noncommittal retorts like “I don’t know” or “It’s just a thing.”

“Your kid may not tell you, but their friends will,” she says.

Make use of that resource — your child might be telling her friend’s parents all about the latest Internet fad.

Borba notes that this story, while tragic, provides a teachable moment.

“This is an incredible opportunity to sit down and talk to your kids because [this story] involves real kids,” she says.  

James Steyer, founder and CEO of Common Sense Media, a nonprofit focused on media issues, says that parents should start teaching media literacy to children when they are 3 or 4 — “younger than you think.” 

“Your kids are going to start asking you about iPads and phones … even when they are in preschool. And, you can have these conversations earlier than you think,” he says.

You won't always be around to explain to your children the difference between fantasy and reality, fact and fiction. Steyer says the first step is teaching children to question what they see. 

“It’s very important to teach them to think critically. That is the essence of media literacy,” he says.  

He warns that more “vulnerable” children might struggle to understand the difference between fantasy and reality. Playing violent video games, watching scary movies or getting lost in online horror stories might be fine for some kids, but trigger bad behaviors in others; parents need to be more vigilant with sensitive kids.

Both Borba and Steyer agree that children should know that using any media, including the Internet, is a privilege, not a right, and there are rules attached.

“It’s good parenting,” Steyer says. “I do think you need to monitor [Internet use].”

Borba suggests staging random usage checks, where parents occasionally check to see what their children are doing online on a surprise basis.  

“Watch your kids' responses. Most kids who aren’t doing anything will give [access] to you … if you walk by and they’re covering up their computer or trying to hide their phone … those are red flags,” she says.

She also says parents should know their children’s passwords to their email and social media accounts.

Both experts agree that using resources provided by Common Sense Media can keep parents informed about the latest trends and best practices for monitoring their children’s Internet use.

Borba adds that while the Internet is a part of this crime, it is not fair to simply blame it. These girls allegedly showed a lack of empathy and planned the attack for months, two signs of sociopathic behavior that goes deeper than a simple fixation on a spooky character. 

“This was such a rare abnormally horrific story,” she says.