We did visit a school on our trip. Bit more formal than the school you visited - was a demountable building and the kids had desks, but still just the one building with all the kids in it and the blackboard at the front. From memory, we'd taken some notebooks and pencils to donate. It was super cute, all the kids introduced themselves, said their name and whether they were a boy or a girl - I guess some people find it hard to tell when the girls don't have long hair

Like your experience, they were all super excited to have us there! It was definitely right on the edge of what I could handle, but my ex did most of the interacting which helped.