The brain begins to mature even before birth. Although it continues to mature throughout most of life, the brain does not mature at the same rate in each individual.
Just because you have a classroom full of students who are about the same age doesn't mean they are equally ready to learn a particular topic, concept, skill, or idea. It is important for teachers and parents to understand that maturation of the brain influences learning readiness. For teachers, this is especially important when designing lessons and selecting which strategies to use.
As a teacher, all children need to be challenged and nurtured in order to profit from your instruction. As a result, it is important to understand how our brains mature as well as the differences that may be present at each stage of "normal" development.