In many Japanese schools, teachers improve their lessons together. A teacher plans a lesson with colleagues from the same grade or subject. The lesson is then taught as a kenkyū jugyō, a research lesson, while all the teachers of the school, or those of one grade or subject, watch.
Afterwards, the observers discuss it, in groups or all together. A paper from the National Institute for Educational Policy Research notes that this lesson study is voluntary training and demands a great deal of work.