Blackboard ‘chalk’ are produced especially for use with blackboards in white and also in various colours. White chalk sticks are made mainly from calcium carbonate derived from mineral chalk rock or limestone, while colored or pastel chalks are made from calcium sulfate in its dihydrate form, CaSO·2HO, derived from gypsum. Chalk sticks containing calcium carbonate typically contain 40–60% of CaCO (calcite). As compared to whiteboards, blackboards still have a variety of advantages: On the other hand, chalk produces dust, the amount depending on the quality of chalk used. Some people find this uncomfortable or may be allergic to it, and according
Vezo people catches that men bring them. With what they earn, women buy rice, the staple food, other essential foodstuff and a variety of luxury items. Children go to school in the one village school building, where there are two designated teachers. However, due to the deterioration of public administration in Madagascar, the building and the teachers are hardly ever occupied. Whenever children are in the building, and if the teacher has not run out of chalk, the teaching largely consists in copying letters, numbers, and short sentences from the blackboard onto the child's own A5 size blackboard. Understandably, the many children