I agree very much with Nicholas Cunningham on the importance of involving mothers -- and older siblings and schoolchildren -- in the use and understanding of growth monitoring, using a clear, graphic, easy-to-use "Road to Health" chart. In remote rural areas of Mexico a lot of families with children live in isolated small farms far away from a health post. Therefore health promoters helped the primary childcare-providers (mothers, older sisters, etc.) to become as independent as possible in regularly weighing and recording the weight of the infants, and acting appropriately on their findings. They even helped families learn to make their own essentially no-cost scales out of local materials, so that mothers, often with the help of school-kids, could weigh the under-fives and keep graphic track of their weights in their own homes, as self-reliantly and knowledgeably as possible.
I emphasize the role of school children in growth monitoring because many of the mothers in remote areas still cannot read or write, and their children can play an invaluable role as information readers/sharers and health action-takers. This is especially true in those (sadly too few) schools that promote Child-to-Child activities with a hands-on, discovery-based focus at the community level. Such activities can include growth monitoring, basics of good, low-budget child nutrition, and the constructing and calibrating of low- and no-cost scales.