Understanding the difference between language acquisition and language learning is essential for effectively working with preschoolers whose first language is not English. Language acquisition is defined as the process whereby children passively and unconsciously acquire their first languages. Contemporary acquisition theories posit that children must receive adequate linguistic input during the critical period, which is a window of time measured from birth up to about the age of twelve or puberty, in order to acquire a first language or languages.
In contrast to language acquisition, language learning is defined as the process whereby humans past the critical period actively and consciously learn second languages. Unlike acquisition, learning requires explicit instruction and education. While acquiring a first language comes innately and naturally to all young children, barring any exceptional physiological or psychological disabilities, learning a second language is usually difficult if not sometimes impossible for older children and adults.
Fortunately for early education teachers, preschoolers who are typically between the ages of three and five are still in the beginning half of the critical period of language acquisition. Even preschool children who have grown up in an English-speaking environment have not fully acquired English as their first language as evidenced by mistakes such as "I have two foots" and "The dog eated." Young children, therefore, can more easily learn a second language or even acquire a second first language. Since motivation is also a factor for learning a second language, teachers can harness the natural curiosity of preschoolers to enhance the language development of both native English speaking and ESL students.