It was very nice to meet people (albeit briefly) at the session on Technology last weekend on the DELTA course, Warwickshire College, Leamington.
One of the questions concerned on-line concrdancers. The following information should prove helpful.
There are a number of concordancers available on the web. These usually have limited functionality, but nevertheless your students can perform searches and the software produces a sample concordance line. Try:
This is based on a small corpus, and can be useful for those who need English for business purposes
This concordancer allows you to choose between several corpora.