Writing must be tailored to the medium. You would not publish an essay on a billboard or a short slogan as a newspaper article. Writing for the Internet must be compatible with Internet reading style, and, if we are writing for students, their characteristics.
Jakob Nielsen asks the question How Little do Users Read? in a recent column. Nielsen describes a study by Harald Weinreich and his colleagues. They instrumented the Web browsers of 25 users and collected data on their browsing habits, as shown here:
Even for first time visits to a site, half of the page-stay times were 12 seconds or less.
Nielsen analyzed the same data further. He removed very short pages (probably error messages) and very long views (probably unattended browsers) and found the following correlation between the number of words on a page and the time spent reading it:
Next he asked what percent of the words on a page could have been read by someone reading at 250 words per minute:
As we see, a user might be able to read most of a very short page, but will not typically take the time to read more than a portion of a longer page.
Of course, different users have different reading habits. The posts on this blog may seem long, but they are written for a somewhat scholarly reader. But, as educators, we should probably keep things short and teach our students to write concisely for the Internet.