Section 82(1)(d) in The Bihar Primary and Middle Education Rules, 1961
(d)If the school committee cannot arrange to finance the regular whitewashing of the walls, the walls shall be given cowdung wash at least once a fortnight by the staff and the pupils. This shall form a part of the school routine and at least one period shall be devoted each fortnight to this work. Efforts should also be made to decorate the walls as is done by villagers in their own house in different parts of the State.