- 28 - Plan I. 1/ Two consecutive 60-minute periods of class instruction per day, five days per week, for one year; and one 60-minute period of instruc- tion per day, five days per week, for the other years. Plan II. Two consecutive 60-minute periods of class instruction per day, two days per week, and one 60-minute period per day, three days per week, for each class each year. Plan II. (Modified) One 60-minute period per day, five days per week for each class for two years, two consecutive 60-minute periods per day two days per week, and one 60-minute period three days per week, for each class for two years. (This assumes that there is a four-year program of vocational agriculture in operation. A teacher may have four classes divided into Agriculture I, II, III, and IV; or three classes, Agriculture I (9th grade), II (10th grade), and III (11th grade and 12th grade combination). If the latter system is employed, Agriculture III should be taught one year and Agriculture IV the next. Plan III. Two consecutive 45-minute periods, of class instruction per day, five days per week, for each class each year. 2.43 Qualifications of Teachers. 2.43-1 Professional Preparation in Agricultural Educa- tion. See footnote, p. 24 of this Section. 2.43-2 Technical Preparation in Agriculture. Each teacher will have a minimum of 20 semester hours in science and not less than 50 semester hours in technical agriculture, the latter to include credit in farm crops, soils, animal husbandry, poultry, agricultural economics, 1/ The double period for vocational agriculture may be arranged for any one of the classes (Agriculture I, II, III, or IV). However, it is recommended by the State Department of Education that the double period be arranged for Agriculture III and IV.