1. The author says that the theory that a child's brain is best suited to learn a language effortlessly and perfectly during the early years because puberty, roughly 10-14 years old, will lose the capacity of the brain. Moreover, Some researchers even claim that as early as the age of five some ability to absorb a new language beings to diminish. Also, young children can development language skills after the age of five. Moderate amounts of exposure to English can be enough to help young children become familiar with the pronunciation of the language, one area where younger children clearly have an advantage over older children.
2. On the other hand, older children and early teens learn languages better in the classroom than younger children. Older children generally have superior cognitive skills, attention span, and motivation. These attributes are essential for successful classroom learning.
Young children can only take advantage of the critical period if they are immersed in an environment that gives sufficient exposure to the language and opportunities for natural interaction over an extended period of time.