The next reforms occurred in 1957 and in 1958 and placed a much stronger emphasis on technical-vocational training, while the years of total schooling were again increased. The period of secondary schooling consisted of a five-year program rather than the previous four, thus extending the entire period of education to twelve years. The network of professional schools was expanded significantly, and teacher training was upgraded and given new emphasis. In 1958 there were specialized professional schools with approximately 64,000 students studying various aspects of industry and agriculture. At approximately the same time there were twenty-two pedagogical schools with an enrollment of 8,989 students. _Table 8. Number of Teachers in Bulgaria, Selected School Years, 1938-70_ --------------------------+-----------+-----------+-----------+---------- Level | 1938/39 | 1948/49 | 1960/61 | 1970/71 --------------------------+-----------|-----------+-----------+---------- Kindergarten | 286 | n.a. | 11,873 | 18,185 Primary | 24,830 | 34,000 | * | * Secondary | 2,874 | 4,893 | * | * | ------ | ------ | ------ | ------ Total primary-secondary | 27,704 | 38,893 | 51,067 | 54,068 Vocational technical | n.a. | n.a. | 2,835 | 2,734 Secondary vocational | n.a. | n.a. | 0 | 5,720 Technical | n.a. | n.a. | 5,307 | 9,045 | ------ | ------ | ------ | ------ Total technical | 2,487 | 1,109 | 8,142 | 17,499 Teacher training | 50 | n.a. | 251 | 406 Higher education | 588 | 1,169 | 3,883 | 7,125 --------------------------+-----------+-----------+-----------+---------- n.a.--not available. * In 1960 the primary and secondary levels were unified under one system. The concept of practical work as an integral part of the curriculum was again emphasized, and the scope of vocational training grew enormously as vocational and technical schools increased threefold. Although all students had to perform certain tasks as part of their basic education, the 1957-58 reforms dictated that graduates of higher technical and agricultural institutions had to perform one year of practical work before graduation. As the concept of polytechnical education became widespread at the secondary level, practical work consumed up to one-third of the total hours of education. Although experimental vocational training was introduced into the curricula of some gymnasiums in this period, other gymnasiums, particularly in the rural areas, required students to spend several hours weekly in formal vocational studies.