Another group of seventh graders (of mixed gender and in a different community) told me the rules regarding how many pictures to post from an event. There was a sense of what was acceptable and what was not. Posting one to three images was fine, they said, but all agreed it was “obnoxious” to “blow up people’s phones” with a huge stream of images from a party or event.

These kinds of images can lead to feelings of exclusion as well. Imagine watching a party unfold, in real time, on Snapchat or Instagram, when you aren’t there. The experience can be absolutely devastating to tween and teenage children. When I asked these seventh graders about it, they said that it happened all the time, and that it can be hard to deal with.

With their lives constantly on display, it’s a challenge for even well-intentioned tweens to avoid making others feel excluded. The “rule” was that it is “better not to lie or make excuses” if you are with one friend and another friend wants to hang out. Better to be honest and say, “I have plans,” than to lie and say, “I have too much homework,” then take a risk when sharing images of yourself out with friends later.

Parents often feel as if their children’s smartphones are portals to another world — one that they know little to nothing about. A study released last month found that fewer than half of the parents surveyed regularly discussed social media content with their tween and teenage children.

But parents need to know that their child’s peers have created their own set of rules for social media, and that they should ask their kids about them. What are you “allowed” to post, and what seems to be off-limits? Are the rules the same for boys and girls? Why or why not? Can you show me an example of a “good” post, or a “bad” one? Does social media ever stress you out (and can you give yourself a break)? How can kids in your group make group texts or social media nicer for everyone?

In a study published last summer, researchers at the University of California, Los Angeles, found that the pleasure centers in teenagers’ brains respond to the reward of getting “likes” on Instagram exactly as they do to thoughts of sex or money. And just as parents try to teach children self-control around those enticements, they must also talk to them about not falling victim to behavior they will regret when craving those “likes.”

As parents, we don’t want our kids to make a big mistake online: writing something mean in a group text, posting a too-sexy picture or forwarding one of someone else. According to a Pew Research Center survey, 24 percent of teenagers are online “almost constantly,” so it’s essential that they know how to handle themselves there.

Getting your children to articulate the unspoken rules can be the first step in helping them be more understanding of their peers. When we observe our children harshly judging others who have a different sensibility about the use of social media, they need us to set aside our judgments about their world, and help them cultivate empathy for one another.