The TEFL Greece collection of corpora links contains links to a wide variety of tools for exploring text, all of which are free to use at least on a trial basis.
There are two interfaces to access the British National Corpus, one hosted at Oxford and one at Brigham Young.
The Oxford one offers a Simple Search facility that makes it ideal for novice users. Simply type in any word or phrase, and the site will give you a sample of fifty complete sentences containing that word or phrase. These authentic examples show the correct use of the language, and can be used for all kinds of activities with your advanced learners. For example, get them to analyse examples with "take part" and "take place" and they will quickly have a clear idea of the difference in meaning. This site also has brief introductory texts on What is the BNC? and Using the BNC.
The Brigham Young interface is slightly more complex as it offers more functions on the homepage, including the ability to perform a KWIC search which presents examples of the Key Word In Context, and the option to search only certain types of language such as spoken, fiction, newspapers and many more. The site also offers a five-minute guided tour which is a very useful introduction to the facilities.
The collection also includes links to a variety of smaller and more specialised corpora, including:
- a corpus of 200+ Graded Readers for English learners
- concordances in French, Spanish and German as well as English
- specialist corpora including one of British news
- a corpus of academic spoken English
Finally, there are a few selected articles introducing the uses of corpora. Hopefully, these will give you additional ideas about the many ways in which these resources can be used to enrich your teaching.