Sampling technique To enroll a sufficiently sized random sample of eligible school children, we will obtain lists of children in Classes 1-3 from the school authority. Participating school children will be selected randomly from these lists through computer-generated random numbers. An equal number of boys and girls will be selected from each class to enable gender analysis. Schoolteachers will assist in identifying and contacting all randomly-selected children and their mothers at household level. In the case of a school child who is randomly selected but is not present at the school due to illness, dropout etc., the subsequent child on class list will be selected. Children whose cognitive abilities are are challenged by autism, mental issues or iodine deficiency will be excluded from the study.