We know that there are a number of myths about second language acquisition that can obfuscate our approach to working with ELLs; such as the notion that different languages ‘interfere’ with each other, or that parents should speak only English language with their children at home, and so on.
One commonly held belief about additional language acquisition is that younger children do a better job of it than older children or adults. While it is true that younger children tend to develop accents that match more closely those of first langauge speakers of English, the research tells us that older children and adults use their existing linguistic schema, experience of acquiring their first language, and world knowledge to help them learn their second or additional language and thus have the potential to do every bit as well as their younger peers.
In this article The New Scientist reports on some research that would suggest that in fact older language learners not only do as well as their younger peers but can do even better as they acquire (and note this is ‘acquire’ rather than ‘learn’) a new language.
In brief, the experiment reported in the article gave adults and young children the task of recognising and applying a new grammar rule, without explicit teaching of the rule. In it the older learners fared much better than the younger ones.
While language experiments of this sort do not necessarily replicate the process of language acquisition in the real world exactly, they do serve to remind us that we should consider and capitalise on what our older students bring with them from their first langauge(s) when they embark on the process of learning English with us. For us as teachers we should ensure that we help older students activiate their existing knowledge, build on existing schema and make connections to their first language and cultural experiences.
For more on how to do that check out everythingesl.net for lots of great guidance.