When food prices go up, what happens to school meals? Who carries the cost of food price inflation?
School meals exist because of a political decision that it is in the public interest to provide them.
Left to the market, there are no school meals for children. Supply of food comes from cafes, vendors and machines outside schools. Some of them may operate inside the school, a privileged position in the market, for which they will be prepared to pay the necessary price. This may be via a payment to the school, or a bribe, or an official fee to a licensing authority e.g. to sell drinks and food in the playground, or install a drinks dispensing machine in the school corridors. The demand comes from money provided by the children's family, or money which children have begged, stolen or earned - (though except for the earned income, which is by definition child labour, all of these are non-market sources of income). In times of food scarcity, prices will rise, the purchasing power of children will fall, and so nutrition levels will fall and under-nourishment, under-acheivement, and even morbidity and mortality rates may rise.
The main traditional way of providing daytime meals to children is a non-market mechanism - the family provides the meal to the child, spending adult wages on basic foodstuffs, or using unpaid family labour for harvesting, cooking, packaging the food.