Idaho Code § 33-1003A
In computing the average daily attendance the entire school year shall be used except that the twenty-eight (28) weeks having the highest average daily attendance, not necessarily consecutive, may be used. When a school is closed, or if a school remains open but attendance is significantly reduced because of storm, flood, failure of the heating plant, loss or damage to the school building, quarantine or order of any city, county or state health agency, or for reason believed by the board of trustees to be in the best interests of the health, safety or welfare of the pupils, the board of trustees having certified to the state department of education the cause and duration of such closure or impacted attendance, the average daily attendance for such day or days of closure or impacted attendance shall be considered as being the same as for the days when the school actually was in session or when attendance was not impacted. A decision by the state department to disallow such a consideration shall be subject to appeal to the state board of education.
For illness or accident that necessitates an absence from school for more than ten (10) consecutive school days, the school district may include homebound students in its total attendance, provided that academic instruction has been given by appropriate certified professional staff employed by the district.
Idaho Code § 33-1003A