1. An agreement for whole grade sharing shall establish a method for determination of costs, if any, associated with the sharing agreement. 2. For one-way sharing, the sending district shall pay no less than one-half of the district cost per pupil of the sending district. 3. For two-way sharing, the costs shall be determined by mutual agreement of the boards. 4. The number of pupils participating in a whole grade sharing agreement shall be determined on the date specified in section 257.6, subsection 1 , and on the second Friday of January of each year. 87 Acts, ch 224, §62 ; 2006 Acts, ch 1152, §40 ; 2016 Acts, ch 1036, §8 Referred to in §256.13 , 257.11 , 280.15 , 282.7 , 282.8