I'm thinking about starting to teach my 7 year old son meditation, specifically concentration and metta. My concern is that, at least based on the experience of many on DhO, early childhood exposure to simple meditation techniques may lead to involuntarily crossing the A&P.

What do y'all think?

I would ask myself very seriously why I wanted to teach a 7-year-old, especially my 7-year-old, meditation.

What's your motivation?

Mostly because he has expressed interest and I think that really knowing how to focus and how to be kind are invaluable skills that are only developed by practicing them until they become second-nature. Our culture tends to reinforce the exact opposite, so I figured the quicker you intervene to counteract the negative influences in the world, the better...but especially since he's showing interest now. 

When I was 8 years old I wanted to be a doctor 

I think kids should grow up and form a good, solid foundation of self and achieve psychological stability and basic mental health before being exposed and expected to be able to handle the kind of results one can get from vipassana and concentration practices. What's the worst that could happen? Do you want that on your conscience? This is obviously your call but I suggest you think it through very carefully. Maybe you start with simple mindfulness meditation and see how that goes before you throw your son into the deep end of the pool.

EDIT: I would also argue that you may not be the best person to teach your son. Might be something else to think about.

Yeah, I'm caught between the fact that I know learning these things would be beneficial for him but also understanding that the worst case could be really bad. Whatever we do will definitely be at his level and his own pace. The more I think about it, I think maybe we should start with basic mindfulness and then move to metta. If he can learn to develop metta then he will know how to be kind and also be able to focus, and having the ability to easily incline the mind toward kindness would probably be the best antidote for the difficulties that can arise after the A&P.

Maybe short practices that are designed for kids like those from https://ibme.info and .B Mindfulness in Schools etc.

I've been teaching my daughter meditation since she was 4 or 5 (although very adapted methods to her age at the time). She is now 8, going 9 in two months, and still meditates occasionally with me. I also brought her to various kids mindfulness activities given by various meditation centers.

I would suggest to present it almost as a game, or include games in it. As far as my daughter is concenrned, she showed interest very early so I have continued to this day. If a kid shows resistance though I would not push it on them. Also, they are very short sessions for her, about ten minutes. 

In my daughter's case, it is part of a larger context where I told her Buddhist stories meant for kids (jatakas with animation books), and also teaching her the principles of morality/sila/non-harming. So there is a whole context which I think helps put the meditation in a larger, healthy context.

According to the Buddha of the Pali canon, crossing the A&P is a very, very desirable thing for all. It puts you solidly on the path to liberation from dukkha. Last meditation session, my daughter started to feel (and observe) an ich on her nose begining to pulse rapidly. She is doing very fine. 

My father made me meditate once when I was around that age. I feel grateful for it.

Overall I would say to stay in tune with the child's reactions and responses to meditation, and take it from there. If meditation is counter-indicated for a particular child, nature is usually kind enough to give early warning signals that are mild. People who have been harmed by meditation usually are the ones pushing themselves too much (often in retreat contexts), or beeing pushed too much, while not being ready. 

I assume you do not plan to make your son meditate 10 hours a day ;-)  

I was thinking about it with regard to my son who is soon 14 and who struggles a lot with overload from his senses and with overthinking (he is autistic like me), but I soon dismissed the idea because there are risks involved. I would guess that he has already crossed A&P because he is very perceptive and has told me some stuff that could indicate it and it is very possible that he already has dark night symptoms, but in case he hasn’t - well, that is something that would require informed consent. I’m not convinced that he would know what he was getting himself into. It is all too tempting to diagnose people around me as having dark night symptoms and help them to get through it, but I’m definitely not qualified to do any such thing, and even if I were, doing it with somebody close to me would probably not be a good idea, especially not a child that depends on me. We do listen to guided sleep hypnoses together when he has trouble sleeping, though. He really likes that. And when he was younger we did some visualization exercises about safe places when he was scared. That was before I knew anything about the risks of meditation. It’s hard to draw a line where it’s safe and not. There are schools that have the children meditate. Is that a good thing or is it irresponsible? I don’t know what to think. I do know, though, that I’m in love with meditation right now, just like a drug addict has a phase of being in love with their new drug, so that’s a reason to be extra careful.

I focus on sila with my kids. I specifically try to help them see how helping others, helps themselves and harming others, harms themselves. Another angle I try is to help them see that being unkind will affect their happiness. 

There are times where I will work in some breathing exercises like if they are upset or if they doing something requiring concentration like playing sports/taking a test.