Adding training, schools and workshops

One entry per class or workshop: what it was called, where, which category it falls under, and the years. The years are years, not dates, so 2018 to 2020 is the shape to use. Category is what groups the list on your site, so keeping it consistent is what makes the difference between a tidy training section and a pile. List the teacher in the class name where the teacher is the reason it is worth listing, which in this industry is often.