Children are typically considered tweens between the ages of nine and twelve. After which time, they are generally considered teenagers. Physical development during the tween period occurs at a rapid yet uneven rate. Also, each child is different and will develop at different stages.
Tween physical development prepares a child for the next stage in his overall development. He moves from simple childhood to the physical and mental challenges that teenage life demands. This period of growth sets the foundation to ensure healthy social and physical growth in the years to come.
Physical development in a tween will range from simple growth to more complex emotional and social development, due to the fact that specific parts of the brain are maturing. The central nervous system will continue to develop which means tweens will have better balance, speed, coordination, and agility than they did when they were younger. You may notice also that your child grows in height at a shocking rate and they may also gain weight in preparation for puberty.
Time Frame
Many children will experience a growth spurt around age ten but every child is different. Other children may not grow until much later, perhaps as late as age twelve or thirteen.  Don't compare your child to others his age, as each child will develop differently.
Physical development at this age is unpredictable so it’s important not to delay broaching the topic of puberty and sexuality with your child. Make it an open and easy topic that your child can check in with you about at her leisure rather than one conversation. This will make it a topic that your child feels comfortable broaching with you whenever she needs to.