The New College Group says that English rules can be tricky. These rules would be known as synonyms, idioms, and pronunciation are what make it difficult to learn. The first example is with words containing “ie” and “ei”. The rule is that you use “I before E, except after C.” Another example is when a word ends in “ough” such as tough and rough. Although these two words sound the same, other words like through are pronounced “throo.” There are many other rules that are difficult such as slang, that really don’t have a meaning or make sense if you know or understand another language. McConnell clearly states that language learning is a part of the brain chemistry for children. Their unconscious state of mind is designed to absorb information, making it easier for young children to learn a second language. In learning a language, there is a critical period where children are able to learn quicker and more naturally than adults. In particular, this is the grammar aspect of learning a language. This is at its peak during childhood and quickly declines during adolescence. There is no clear marking for the amount of time that the critical period is important. It is also unknown what causes this critical period and the decline in new language learning that occurs afterwards.