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The reproductive system of a child is not mature and needs to change as a boy or girl develops into an adult, so that the system is fully working. These changes begin between the ages of ten and fifteen. The time when the changes happen is called puberty.

The changes happen because of sex hormones produced by the testes in boys and by the ovaries in girls. Some changes happen in boys and girls, while others just happen in boys or girls.

Here are some changes that happen to both boys and girls:

  • underarm hair grows

  • pubic hair grows

  • body smell gets stronger.

  • emotional changes

  • growth rate increases

Graph shows that height increases as age increases. As age increases, there is a bigger variation of heights - at age 16 heights range from 14cm to 185cm. Boys are generally taller than girls, except for the ages 12 and 13 when girls are taller than boys.

The time when the physical changes and emotional changes happen is called adolescence.


Here are some changes that happen only to boys:

  • voice breaks (gets deeper)

  • testes and penis get bigger

  • testes start to produce sperm cells

  • shoulders get wider

  • hair grows on face and chest.


Here are some changes that happen only to girls:

  • breasts develop

  • ovaries start to release egg cells (periods start)

  • hips get wider.




Reproduction activity

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