Background: Another obvious change that occurs during puberty is rapid growth. This is called the adolescent growth spurt . In boys, it is controlled by testosterone. The rate of growth usually starts to increase relatively early in puberty. At its peak rate, growth in height is about 10 centimeters (almost 4 inches) per year in the average male. Growth generally remains rapid for several years. Growth and development of muscles occur toward the end of the growth spurt in height. Muscles may continue to develop and gain strength after growth in height is finished.

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Which boy's height will increase more over the next year?
Answer: Joseph

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Which boy's height will increase less over the next year?
Answer: Walter

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Which boy is currently more likely to be taller?
Answer: Walter

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Which boy is currently more likely to be shorter?
Answer: Joseph

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Whose muscles are more developed?
Answer: Walter

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Whose muscles are less developed?
Answer: Joseph

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Is Walter's rate of growth increasing or decreasing?
Answer: decreasing

Situation: Joseph and Walter are two brothers who have always gotten along well, but are now going to be separated for the first time in their lives. Walter has just graduated high school and is going off to live at college several states away from home. Joseph is about to be a freshman in high school, so he has several years before he will even have the possibility of going off to the same college as his brother.

Question: Is Joseph's rate of growth increasing or decreasing?
Answer: increasing