### Study Abstract

 After birth, an infant is known to lose weight for a few days before starting to grow. We make use of this information in order to develop a mathematical module that illustrates the concept of "minimum". At the same time, this module will allow one to learn the use of calculus in real situations. When monitoring the health of a newborn baby, it is very important for a medical practitioner to know, roughly, when a baby should stop losing weight. For, if a baby continues to lose weight beyond the day determined by available medical data, that may be worrisome and measures should be taken to ensure the well-being of the baby. First, we will suppose that the functional relationship between the average weight of a baby and the number of days from birth is known. How does one obtain such a relationship? Then, we will estimate the day on which the average weight of the baby will be the lowest (minimum) using a trial and error approach. Will this be a good estimate? We will demonstrate how to employ the idea of "derivative"(what is a derivative of a function?) from calculus to systematically find the exact time (after birth) on which the minimum weight occurs. Also, we will determine that minimum weight. The newborn baby will start to grow beyond the day on which the minimum weight occurs.