Why do younger children learn languages so easily? It comes down to the plasticity of the brain. To put it simply, the brain’s language center (Wernicke and Broca areas) is centrally located between lobes in your brain. Before and during puberty many structural changes occur in the brain that stabilize the lobes. Once the lobes are more fixed, thinking changes drastically, such as the ability to reason abstractly at deeper levels (which is great for learning Algebra!). However, as the lobes are set, the language center becomes much more rigid. While young children easily absorb new languages, acquiring a native accent and applying grammar after this period is extremely difficult if not impossible. Scientist name this phase from birth to before puberty as the critical period for language acquisition. In my own story, I studied Spanish for 7 years (HS and College) and then lived in Venezuela for 7 years, achieving fluency, but maintaining a strong American accent and speaking according to English grammatical structures (not to mention often confusing masculine and feminine articles). And I might add, it was not easy at all starting to learn a second language at 15 years old.