Workers in this minor group conduct classes and give private lessons to instruct students at the third, second, first or pre-primary level, educate handicapped persons, undertake research and advise on teaching methods and instructional aids, organise and direct teaching activities in schools, and perform related tasks.In some countries, a stratified system of educational levels is a relatively recent development. In the case of English elementary schools, for example, Teachers might be coded to unit group 1-33, or to 1-30.20. Physical training instructors and sports coaches instructing in educational establishments are classified in unit group 1-80.