One way to combat this is to limit their internet searches to a custom search engine, such as the ones that can be created through Google. A teacher can not only prevent students from going to undesirable sites, but they actually can dictate exactly what sites they can access. By creating a custom Google search engine, only the sites a teacher chooses will be displayed in the results. This also benefits the students because they do not have to wade through an exorbitant number of results to find the information you want them to find. Using custom search engines can benefit everyone involved. This is definitely a tool worth incorporating in the classroom.
Cameron's Custom Search Engine for the Revolutionary War: