I am pretty sure that early childhood education (until fifth grade) is a very active area of research in all highly developed nations. Almost, by definition, it you want to (a) become or (b) stay a highly developed nation, you need to have a high quality public education system.

My mother was a first grade teacher for 30+ years. In her school system, first grade is the year that students learn to read. Each year, she was also required to take professional training classes for a certain number of days. She told me that, in her career, there were many changes and improvements and new techniques developed to help children learn how to read. One thing that changed a lot: The techniques are way more inclusive, so non-normie kids can learn to read better at an earlier age.