Answer to Question 1
The growth spurt begins at an average of 10 for girls and 12 for boys.
It continues through about age 16 for girls and age 17 for boys, although minor growth of the limbs can continue into the 20s for both sexes.
Many girls are taller than the average boy in grades 6 to 8, but by age 14, the average boy is taller than the average girl.
Answer to Question 2
language acquisition