Children can do very well learning Tai Chi. In 1981 I volunteered to teach Tai Chi to students at Cultivating Virtue School at the City of 10,000 Buddhas, in Talmage, CA. Here's a picture of us doing warm-up stretching exercises.
I would like to see more children, young adults, and people in their 20's, and 30's taking up Tai Chi. It is not just for older people.