Abstract: An apparatus for use with baby bottles, a baby bottle assembly, and a method of preparing liquid infant formula for feeding to a baby are disclosed. A measuring and mixing pod allows the appropriate amount of powdered infant formula to be measured out in advance and stored within the baby bottle from which it is to be served. The same bottle may be filled with water or other liquid while keeping the powdered formula dry. Further, a simple and quick method is provided for mixing the powdered formula with the liquid stored in the bottle when it is time to feed the baby.