My son has turned five, and REALLY wants to take Jiu Jitsu. There's a really good gym not far away, and while the instructor definitely knows his jitz... I don't get the impression that he really "gets" kids that well.
Last night I found a closer gym, with good pricing. I talked with the instructor for a while, he seemed intelligent, knowledgeable, and very understanding of teaching kids. He's a black belt under Flavio Behring, and also has a black belt in Judo. In addition to two jitz classes each week, once a week, he also teaches the kids about things like "stranger danger", how to handle adult attackers and abductors, stuff like that.
Now, here are the two things that make me pause: First, the instructor is close to 400 pounds, if not OVER it. He seems to have what it takes to be a good instructor, but that does make me question his activity.
Second, his daughter teaches the women's class. And his daughter is... a blue belt. I asked "You have a blue belt teaching the class?", to which he responded "She has over ten years of mat experience, rolling and striking." I've never had a class taught by anything but a black belt.
So... you guys, tell me your thoughts. I see green flags and red flags, and I'm torn.
I'm mostly there with North.
First of all, have your kid train there for a couple of sessions with you watching the training. If you have at least some experience in martial arts you should be able to judge the training way better with a life view than we in the forum ever could due to hearsay. Then a good trainer/gym shouldn't be afraid to let your kid train a few times with you watching before asking to make a contract.
Then secondly and maybe even more important. At the age of 5 martial arts is not so much about learning how to fight, if at all. At that age having a kid train in a martial arts gym is more about social contact with other kids, having their natural energy used in a good and fun way, learning respect and responsibility towards other people, becoming disciplined etc. The benefits are mainly in getting or staying fit (preventing health problems, particularly cardiovascular, in the long term by not getting fat), becoming self confident, getting a good body cordination (which is besides getting fat a huge problem for the kids nowadays who are sitting in front of TV and play computer games all day) and learning how to fall properly (probably one of the most useful skills to learn in martial arts).
That "stranger danger" thing sounds good to me as it's probably not so much about physical fighting, but rather making the kids become aware of danger to be able to avoid it.
To that daughter being only a blue belt teaching issue. Generally speaking, belts are there to keep the Gi closed. What does it concern you that much anyway, your son probably won't train in the women's class
Then, you don't know what experience she has. Maybe she is a Judo black belt, but has to wear that BJJ blue belt officially in that BJJ class. At least she told you that she has over ten years of experience on the mat. Back in my childhood/adolescent gym for example it was quite common to have intermediate students at least as assistant teachers in the Judo beginner's faction. Did it do anything bad to the learners¿ No, not at all. Sometimes intermediates have a better understanding of beginner's problems because it's not that long ago that they had the same problems to solve themselves. Also in trying and being able to explain things to others oneself learns better later on. Success speaks for my old gym. They were and still are constantly breeding successful fighters for our national Judo league.
So back to your son. Just try it out, bring him there and watch the training. If you feel comfortable with it and if he has fun, that's all you need for the moment. If in a couple of years he wants to become a competitive fighter and you two feel that this gym is not enough for it, there is still time to adjust.