A healthy development measurement tool is a way to measure how well a person is growing and developing. It helps doctors and parents track a person's physical, mental and emotional growth. It can include measurements of a person's height, weight, head circumference and other physical indicators. It can also include tests that measure how well a person is doing in things like school, sports and other activities. By measuring a person's development, doctors and parents can make sure that a child is growing and developing in a healthy way.