The law states that 'the Chaperone is acting in loco prentice and should exercise the care which a good parent might reasonably be expected to give that child'.
The child will be working in a very adult environment and you need to be able to ensure that they understand what is expected of them, taking into account their age and experience.
You need to take account of a child's concentration span, their exposure to adult conversations and expectations and peer pressure.
Health and safety issues on stage or on set i.e. electrical equipment such as leads, sound equipment and cameras can all be very dangerous.
The child may not be in school but that doesn't mean the hours they are tutored are less important that those spent at school.
You need to be able to tell when the child is ill, tired or upset. Don't ignore them in order to meet the production's schedule. It can often be difficult for children to communicate their feelings in a way in which adults understand, therefore, you will be the intermediary between them and the production company.
The concentration span of children is far shorter than that of adults (depending on age) therefore you need the skills to be able to occupy, or enable them to occupy their non-performance time which is especially important during filming and when on location. This may include physical activities or it may be that the child should just rest and quietly read a book.
Different skills will be required when chaperoning in a theatre as opposed to a film set or on location. There is much more 'hanging about' time during filming and the weather may lead to the child being confined in a caravan for quite long periods - remember their energy level is far higher than ours and the children may need more individual attention.
Bullying - you must always be aware of bullying as it can be very subtle. It may be easy to spot a physical fight or sideways kick but it is not always quite so easy to spot the odd word or joke directed periodically toward one particular child. This sort of behaviour should be nipped in the bud immediately otherwise it could effect both the child and the production.
Finally, performing should be an enjoyable experience for the child and for you. Good communication and negotiating skills, be they with the child or with the variety of adults involved in a production, are vital.