What is the Invisible Web?

The deep web (or invisible web or hidden web) is the name given to pages on the World Wide Web that are not indexed by search engines. It consists of pages which are not linked to by other pages, non-indexed or query only pages. It also includes sites that require registration or otherwise limit access to their pages. 95% of deep web resources are FREE. Therefore, there is no excuse for not exposing students and ourselves to these great Internet resources. Google should NOT be a students first line of defense when looking for information. More information from the 21st Century Information Fluency Project

How to Find the Invisible Web

Think "databases" and keep your eyes open.
You can find searchable databases containing invisible web pages in the course of routine searching in most general web directories. Ones of particular value in academic research include:

Greater Google searches

If your students are going to use Google they can use it to locate searchable databases by searching a subject term and the word "database". If the database uses the word database in its own pages, you are likely to find it in Google and it is more likely to contain information that is useful to your students

For example a search for the terms minerals + "data base" turned up two great data base resources without the commercial minerals resources.

Deep Web Directories

There are many deep web directories including
Some of the databases listed here are by subscription. However there is a good chance that your library subscribes to many of the resources or can work with you to get the information you need from one of their sources.

Take a look at The Tutorial from the Library at UC Berkeley and read the Wikipedia article on the Deep Web to help give you a better understanding of the valuable resources available for your students