Here, then, are some ideas for using computers effectively. This site has over 300 links, most of which have multiple links also. Provide students a specific assignment, even if it's just grid-based reporting of information learned. Something to keep them focused on the topic will help, especially if you're using the Internet, to avoid unauthorized searching in in appropriate places on the web. Also concerning the Internet, most newspapers now carry articles regularly about good Internet sites.
Some papers have weekly sections devoted to that, sometimes with specific educational themes.
Have an assignment at the computer, and students work on it 1 at a time, during class until the whole class has completed it. Each student will thus be away from the main class activities for a class period or less, but the teacher can plan on helping them catch up. The assignment can require a short report on what the student did or learned, or scores if using some of the question-based software. This is also possible with one computer, but it goes best with 3 or four computers available. Students can work on projects involving desktop publishing skills, such as making a newspaper covering a specific year in history.