The Therapeutic Riding Association of Virginia has a great list of skills to teach riders through 3 levels posted on their website. The have created a Rider Achievement Certification program along with it. It’s a great resource!
However, the links don’t all go to the right download, so I’ll link them here too:
Note: This is not professional advice, this is a blog. I am not liable for what you do with or how you use this information. The activities explained in this blog may not be fit for every rider, riding instructor, or riding center depending on their current condition and resources. Use your best personal judgement!