American Libraries wrote an article about discovery systems about how you can work with spelling errors, mistakes. Very few discovery systems actually correct for spelling. One way around this is to introduce students to browsers which incoporate spell check while we wait for databases to catch up with other types of searching.
There is a long series of issues that users encounter when they are attempting to navigate discovery systems. Many of them grew up digital natives.
Users think its going to work just like Google, so in your instruction session your goal is to help students become information literate, and to educate them on keywords, searching phrases.
More information about this topic can be found at Web Scale Discovery.