Corpus

First of all, the simple meaning of corpus is a collection of texts written or spoken, put it into a computer. It is based on the language in specific. It can show us what are the most common words used by people in written and speaking. Corpus helps us to know the frequency of words, and how we can use it depend on the context, etc.
In my opinion, I think corpus is important for language teaching, because we are going to teach English, therefore, we have to use the most frequent words in a language, especially if we are going to teach to children. The idea is to know words that are used nowadays. It means that we have to use the words of someone who speak the language (native people). For that reason, as future teachers, we have to know these words to use in a class, for example, teaching the most frequent colors, food, verbs, etc.