We have a 'Weekend' Club where those 11+ can come and be taught by the yard staff and the older teengers the basics of care.
They are not expected to do all the work but initially will groom the retired ponies, then move on to grooming and tacking up ponies for rides, Help with stables, doing waters etc and eventually learning how to muck out. By 13 they will be able to catch in and turn out and do their own allocated pony totally.
They help with one lesson each session, again starting off as a 'spare' helper shadowing an older helper and then getting their 'own' rider who they stay with for the introductionary lessons.
At the end of the day (11-5pm) they have a 2 hour session which varies from jumping to a mini show to teaching each other ( under my eagle eye!!) to lunging/longreining, vaulting etc.
By 15/16 they are often offered paid work when full time staff go on holiday or for summer camps etc.
AND gemsloveshorses often if they cant do other things they come and spend the day tackcleaning ( one girl did six weekends after she broke a leg falling off a friends pony!)
Ask around someone will want your help.