When a child is learning developmental skills, we know the brain development is progressing well. Developmental skills may be divided into the following categories: how a child is talking (Language), learning (Cognitive), interacting with others (Social-Emotional), moves (Gross Motor and Fine Motor) and able to do things on his own (Adaptive). We can determine a brain's progress by how quickly a child is learning new skills. We can do this by tracking his milestones in each of the categories of development. The Centers for Disease Control have a free app that is very helpful. Check it out: https://www.cdc.gov/ncbddd/actearly/milestones-app.html