Decide what kind of search students will need - are they starting from scratch? Do they have a general topic they're trying to narrow down or learn more about?
Make sure to have some specific instructions or options students can use, especially if they're unfamiliar with the web. You might find a few sites that could help them, or provide a handout with instructions on how to use the search engines. For more assistance on conducting electronic searches, visit: https://writing.colostate.edu/guides/trad_research/searches/page2.cfm
If you desire, find specific Websites related to the class-topic or that you think will be especially helpful and assign students to look specifically at those sites.
Or, if students already have general topics, have them search for sites related to their topic to discover the different positions and smaller issues within.