she has Magic but could do with some proper lessons to bring her on a bit more so she can enjoy magic.
I am a bit puzzled by this thread and about what you want?
What can a riding school teach a five year old that you cant?
One of our best riding BHS schools doesnt take children until they are 8 years old -partly on medical ground so not to stress the hips, partly because that is the age at which a child can start to control a horse independently.
You could indeed look for a school that is a Pony Club centre where there will be other children in her age group learning and a social life. You will also get some idea of what a five year old can cope with, attention wise.
Or is it that you want a school to take responsibility for your niece, rather than do it yourself.
My grand daughter started proper grown up lesson when she was 8.
Up till then it was lots of 30 minutes lead out lessons. She learned how to get on and off, how to hold the reins, trot sitting and rising and how to sit when going up and down steep banks or kerbs i.e. balance on a horse, confidence and shere enjoyment - but I would have thought these were things that you could teach on a lead rope hack?
There are technical things you can teach young children such as trotting diagonal - but I actually wasnt very happy with that. It seemed to me that a child needs to know why things are done and before learning diagonals, it is best to understand footfall in walk and trot and to be able to feel it through one's seat. I'd also like her to learn how to handle a horse on the ground.
So I looked for a teacher whose way of riding and teaching I found in line with my own. It is not good sending the child to someone who teaches by the BHS rules, if you are wedded to other methods. We have already had a thread where someone complained that children from a local riding school are taught to do things (e.g. kick or use a whip) she doesnt like to see on her horse.
So it could be confusing for the parents, if the teacher they pay tells them one thing and you - possibly with superior knowledge and experience to a young teacher - prefer something else.
I did take another grand child to a school lesson aged 5 - Good BHS school and ponyh club centre. It was a one off lesson, a birthday treat. She had an inexperienced girl teaching her and a pony that repeatedly put its head down and tugged the reins from her hands. It wasnt a success and the child has not asked to ride again. I cant think of anything better for your niece aged 5 than to go on riding with you.