Such regular attendance shall be during all the days and hours that the public schools are in session in the district, unless it is shown to the satisfaction of the board of education of the district that the mental condition of the child is such that he cannot benefit from instruction in the school or that the bodily condition of the child is such as to prevent his attendance at school, but nothing herein shall be construed as permitting the temporary or permanent exclusion from school by the board of education of any district of any child between the ages of five and 20, except as explicitly otherwise provided by law.

L.1967, c.271.