BJJ is a grappling style that grew out of judo. It emphasises training on the ground (there are no strikes), meaning it is considerably safer that many other styles.
The class starts with a light warm-up and several fun, simple games to help get little kids familiar with the movements of BJJ. Safety is paramount, so children will be paired by size. Class ends with light stretching, before lining up and shaking hands to finish.
At every session, there will be at least two adults present, usually three.