In this class I recommend: 
An exercise mat, a water bottle, exercise clothes, appropriate exercise shoes, or better still; your favorite superhero costume.
As it will be a class with a lot of jumping and moving, I advise that the student have plenty of open space to avoid bumping into anything dangerous. 

Stretching to avoid an injury is a top priority for me, so please advise your child to comply with the stretching instructions before the exercise section of the class.
If your child is particularly boisterous and excitable, I would advise that an adult be present. Just in case your child gets too carried away and I can't control the situation.