Generally people believe that if children go to gym, their height growth will stop and they will not gain height. Children are generally dissuaded from going to a gym.
Yet, in my fitness center, I cater to children from 6 years of age.
How do I do that? Let me clarify few things and doubts here.
Yes, it is true that small children should not be lifting weights (heavy weights and lots of reps). That it can reduce their height growth. But there are exercises that children should do that will help them to increase height, improve posture, increase stamina and concentration. These exercises are yoga, pilates, stretching, aerial silk, swimming, aqua aerobics, dancing, etc.
So, yes, children should not be going to gym to lift weights but should be indulging in other activities as stated that can be very helpful for them.